Plant Science Bulletin archive
Issue: 1970 v16 No 3 Fall
PLANT SCIENCE BULLETIN
A Publication of the Botanical Society of America, Inc.
October, 1970 Volume Sixteen Number Three
Flowering and Photoperiodism of Plants1
(On the Fiftieth Anniversary of the Discovery of Phoroperiodism )
There is a turning point, a cardinal period in the onto-genesis of all seed plants when they turn from vegetative growth to generative development. The discovery of photoperiodism, i.e., the response of plants to the duration of daylight or to the length of day, was of particular importance in the sense of flowering ecology and physiology (Garner and Allard, 1920; 1923). Day length appeared to affect various aspects of ontogeny: growth, flowering, fruiting; the development of above-ground organs—stems, and Ieaves, underground organs—roots, tubers, bulbs, rhizomes; sexual differentiation, anatomical-morphological structure, and the physiological processes related to all of these changes (Samygin, 1946; Konstantinov, Sokolova, and Sakova, 1965).
The influence of the length of day on the transition of plants from vegetative growth to generative development is, however, the most significant and fundamental phenomenon. Therefore, flowering was assumed by Garner and Allard to be the main expression or criterion of photoperiodism. By the capability of plants to flower under one or another length of day they are classified into various photoperiodic groups; long-day, short-day, day-neutral, and others. Photoperiodism appeared to be such a powerful and reliable, means of controlling the course of plant development that after its discovery the entire subsequent investigation of internal factors of flowering and of plant photoperiodism proceeded to be inseparably linked.
In this respect general phenomena observed during the early period of studying the ecology and physiology of photoperiodism such as: the substantiation of photoperiodism as an adaptive response, the differentiation of
1 This paper is a revised version of the Invited Paper presented by Professor Chailakhyan at the XI International Botanical Congress, Seattle, Washington, on August 28, 1969.
leaf and stem phases of the photoperiodic process, the clarification of the importance of light and darkness, and the demonstration of trophic and hormonal factors which form the basis of photoperiodism, are of great importance (Chailakhyan, 1967; 1968). In the same connection the following more recent theories and ideas on plant flowering, that are at the same time theories and ideas on photoperiodism, are gaining great interest: 1) the theory of endogenous rhythms (Bunning, 1950. 1956, 1958), the basis of which is formed by the idea of the relation of photoperiodic response to the diurnal endogenous rhythm; 2) the phytochrome theory (Borthwick, Hendricks, Parker, 1952), on the dependence of the course of photo-periodic response on a special pigment, phytochrome, that has two mutually interconvertible forms; 3) the hypothesis on the correlation of the rates of light and dark responses (T.yubimenko and Scheglova, 1927; Chailakhyan, 1956; Konstantinova, 1966) which is distinct for long-day and short-day species; 4) the conception of the two-phase character of flowering: a) the phase of flower-bearing stem initiation and b) the phase of flower initiation (Chailakhyan, 1964).
There is yet no solution to the basic mystery of photoperiodism: why do typical long-day plants flower under a long day and fail to do so under a short day, while short-day plants flower under a short day and fail to do so under a long day? The diametrically opposite response of long- and short-day species to length of day, the duality in their behavior, as Maksimov (1925) wrote in his review on photoperiodism, has surprised everyone and still remains unsolved.
The mystery is deepened by the fact that it was demonstrated that physiological processes and biochemical reactions which precede flowering respond to length of day in the same manner in long- and short-day species. The increase in activity of metal-containing enzymes and of the content of carbohydrates and growth hormones in all plants regardless of the nature of their photoperiodic response proceeds more intensively under long days, while the increase in activity of residual respiration enzymes and in content of nitrogenous compounds, the products of nucleic metabolism, and substances of the anthesine type that stimulate floral initiation proceeds more intensively under short days (Chailakhyan, 1964).
Investigations carried out recently in the Laboratory of Growth and Development of the Institute of Plant Physiology of the Academy of Sciences of the USSR have shown that light, darkness, and length of day affect
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the activity of oxidation-reduction processes and the coupling of respiration and phosphorylation in the same direction in the long-day as well as in the short-day species.
The photochemical activity of chloroplasts was always greater in all plants under long-day conditions regardless of their photoperiodic response (Bavrina, 1969). The coupling of respiration and phosphorylation in the plants of both mentioned groups changes in the same manner according to the Iength of day: during the daylight hours the coupling increases; under darkness, particularly during a lengthy night of the short-day cycle, the coupling gradually decreases ( Aksenova, Konstantinova, Nikitina, 1968) . It appeared that uncoupling of respiration and phosphorylation during a short-day cycle, achieved by introducing 2,4-dinitrophenol into plants, failed to affect flowering under light conditions while under darkness changes the course of dark responses; the inhibitor fails to produce marked changes in the long-day cycle whether applied during the light or dark period. Application of diuron, an inhibitor of photophosphorylation, has led to substantial changes in the flowering of plants under long days, where light responses play a determinative role, but flowering was unaffected under short-day conditions where darkness responses are of primary importance (Konstantinova, Aksenova, Nikitina, 1968; Bavrina, Aksenova, Konstantinova, 1969). Thus, light responses of the photo-periodic process in plants of both photoperiodic groups require energy of photophosphorylation while dark responses require energy of oxidative phosphorylation (Chailakhyan, Aksenova, Bavrina, Konstantinova, 1969).
As a result, changes in physiological and biochemical processes and in nutrient and regulatory substances in all plants occur under the influence of the length of day in the same direction. On the other hand, some plants flower under a long day and others under a short day. Concluding that the conversion to floral initiation in long- and short-day species is preceded by opposite metabolism is entirely unsuitable from the general biological point of view. Yet, one has to admit that the investigation of physiological and biochemical processes affected by the length of day has not decreased the mystery of photoperiodism.
Nevertheless, there are approaches to the solution of this mystery: an historical or evolutionary approach that offers an ecological explanation of the formation of various photoperiodic groups including long- and short-day species, and an experimental approach which draws us nearer to the physiological explanation of the opposite behavior of these species.
The Genesis of Photoperiodic Groups
The historical or evolutionary approach is based on in. vestigations of photoperiodic response of various plant species and cultivars distinguished by their origin and ecology. Experiments showing close relation between the character of photoperiodic response and the geographical origin of plants have shown photoperiodism to be an adaptive response. Moreover, specialization of plants growing in temperate and high latitudes tends toward the formation of long-day species incapable of flowering under a short day, and the specialization of plants of subtropics and tropics is directed towards the establishment of short-day species (Lyubimenko and Scheglova, 1927; Doreshenko and Razumov, 1929; Allard, 1932; Konstantinov, 1934; Razumov, 1954). Short- and long-day species originated from day-neutral species which are more ancient by origin, and the adaptation of the former species to length of day gave them advantages over neutral forms. The fact that long-day plants fail to flower under a short autumn and winter day but instead produce small bushes and rosettes promotes their preservation under a snow cover and represents their adaptation to overwintering in temperate and northern latitudes. Short-day plants fail to flower under long summer days but continue vegetatively and survive hot and dry summers or periods of pouring rains in subtropical and tropical countries.
The adaptive significance of photoperiodism goes far beyond controlling the dates of flowering. It plays an out-standing role in permitting individual or species survival under adverse environmental conditions. The changing length of day gives the plants signs of the necessity of preparing for seasonal changes. The length of day, as an astronomical phenomenon, is a reliable and accurate guide pointing out to plants when they should flower and re-produce- and when to be prepared for adverse environmental conditions (Katunsky, 1939; Moshkov, 1940; Samygin, 1946; Biinning, 1948; Chailakhyan, 1956; Skripchinsky, 1958, 1960).
The conversion to generative development does not depend only upon the variation of the length of day. The flowering in a large group of species neutral to the length of day and failing to exhibit photoperiodic adaptation is governed by other environmental conditions—temperature, intensity and quality of light, nutrition and water regime. The response of these species to environ-
mental conditions is also adaptive and permits the con-version of neutral plants to the stage of sexual maturity. The same environmental conditions also play an important role in the flowering process of photoperiodically sensitive species, because the photoperiodic response of long-day, short-day, and other species may occur only under a definite level of temperature, light intensity and quality, nutrition and water regime.
Long,-short-day species (Bryophyllum, Kalancboe, A1oë, Cestrum, etc.) are known. They flower only under successive exposure to long and then to short days (Dostal. 1949, 1950; Resende, 1952, 1954; Sachs, 1956). There are also short; long-day species (Scabiosa, Campanula, Tri f oliur, etc.) which flower only under successive re-placement of short days by long days (Chouard, 1957; Wellensiek. 1960: Thomas, 1961 ). Medium-day (stenophotoperiodic) and extreme day length. (amphiphotoperiodic) species are also known. The former flower under an intermediate day and the latter flower only under a long day or a short day but fail to flower under an inter-mediate day (Lang, 1965). The adaptive character of the plant response to the length of day which is more general in long- and short-day species and more specialized in other species is especially distinctive under this classification.
The photoperiodic response of plants was initially considered as a static response to permanent short or long day lengths. The classification into long- and short-day species was related to the same concept. But it soon turned out that the alternating length of day which occurs in nature is of great importance. Thus, McClelland (1924) showed that Tephro.tia candida, a tropical species, flowered only under a 12-hour day. Flowering is even and abundant if the plants previously were exposed to a 13.5-hour day and, if the plants were first exposed to a 10-hour day, flowering proceeds poorly or not at all.
The adaptive response to day length is very pronounced in long,-short-day and short,-long-day species. In the former this response means an adaptation to the changing length of day in the summer-fall season. In the latter it means an adaptation to the changing length of day in the spring-summer season. The presence of ecotypes with various photoperiodic responses within the same population should also be regarded as an adaptation to changing daylength of the growing season (Sinskaya, 1960). All this indicates the dynamic character of photoperiodic adaptation.
Photoperiodic adaptation has developed along with the formation and establishment of various plant forms with morphological features and physiological characters peculiar to them. Photoperiodic adaptation is representative not only of the angiosperms but of lower plants, including fungi and algae. There have been developed species of angiosperms with a quantitative photoperiodic response, i.e., capable of flowering under any length of day, but with some acceleration under long days in long-day species and with some acceleration under a short day in short-day species. Species with a qualitative photoperiodic response, typical long-day species capable of flowering only under long days, and typical short-day species capable of flowering only under short days that have lost their responsiveness under usual conditions have been developed.
The question of what morphological and physiological changes are related to the loss of flowering ability of long- and short-day species is of substantial importance in the approaches to the solution of the main mystery of phoroperiodism. Adaptation of typical long-day species to overwintering is related to their loss of ability for stem formation and growth, while the adaptation of typical short-day species to existing through the summer period of tropical rains and lasting drouths is related to their loss of the ability to produce flowers (Chailakhyan, 1960, 1961). The separation of the process of flowering into two phases occurs in both cases: a phase of flower-bearing stem formation and a phase of floral initiation. Formation of flower-bearing stems in long-day species proceeds more rapidly or only under a long day while the floral initiation in short-day species proceeds more rapidly and only under a short day.
Thus, the loss of ability to flower under an adverse length of day in photoperiodically sensitive species occurs not completely but partially: in long-day species it is the loss of the ability of stem formation and growth under the short-day conditions, in short-day species it is the loss of the ability of floral initiation under a long day.
The Conception of the Two-Phase Character of Flowering
The comparative experimental investigations on the role of trophic and hormonal factors in the flowering of long- and short-day species and the results of the experiments on the genesis of photoperiodic groups enabled us to set up an idea about the two-phase character of flowering (Chailakhyan, 1964). Each of these morphological phases corresponds to a certain physiological condition. The first phase is characterized by intensive production of gibberellins in leaves accompanied by an intensification of carbohydrate metabolism and the rate of respiration at the expense of metal-containing enzymes and by an increase in auxins in stem buds. The second phase is characterized by intensive production of anthesins in leaves, which are essential for floral initiation. This process is accompanied by the intensification of nitrogenous metabolism and of the activity of residual respiration as well as by an increase in nucleic acids (see Table 1_) .
The content of gibberellins plays a decisive role for physiological changes in the first phase of flowering. Anthesins that affect the floral initiation (not yet isolated) play a decisive role in the second phase of flowering. The two phases in day-neutral species proceed regard-less of the length of day.
The critical phase in long-day species is the first one. the phase of flower-bearing stem formation, which proceeds only under a long day ("L") when the intensive production of gibberellins occurs. Capacity for the second phase of flowering in long-day species is firmly fixed just as in day-neutral species, and it proceeds equally under a long as well as under a short day. The second phase of flowering in long-day species is nor critical because they initiate flowers under a short day after a gibberellin treatment of central buds.
The second phase of flowering, flower initiation, is critical in short-day species, and it proceeds only under a short day. The ability to conduct the first phase of flowering in short-day species is firmly fixed just as in day-neutral species and proceeds equally under a long as well as under a short day. The first phase of flowering in plants of short-day species is not critical because these species produce sterns under long as well as under short days.
All this suggests that although the course of physiological and biochemical processes proceeds in both photo-periodic groups in response to the length of day in the same direction, the results are different. Metabolic changes occurring in response to long days that determine the events of the first phase of flowering, stem formation and growth, are important for the flowering of long-day species; the occurrence of the second phase, flower initiation, is ensured by metabolism which is controlled not by the length of the day but by immediately translated hereditary information. The metabolic changes in response to a short day determine the second phase of flowering and are important for the flowering of short-day species; the passage of the 'first phase, stem formation and growth, is ensured by metabolism which is controlled not by the length of day but by the immediately read genetical information. Beyond this control there are various phases of flowering and biosynthesis of various constituents of the two-components system. of the flowering hormones in the two photoperiodic groups (Chailakhyan, 1967, 1968; Chailakhyan, Aksenova, Bavrina, Konstantinova, 1969).
Environmental Factors and Internal Factors
The discrepancy and duality of photoperiodism of long-and short-day species are completely determined by the discrepancy and duality of the very criterion of photoperiodism, i.e., flowering. This criterion is distinct in reference to the two groups of long- and short-day species, the difference of the criteria being determined not only by environmental factors, that is factors by the length of the day, but also by internal factors.
Photoperiodically neutral species have no adaptation to the length of day, and their passage through both phases of flowering is related to direct translation of genetic in-formation. If the neutral response in reference to the length of day is marked by the letter "N," the long-day response by the letter "L," and the short-day response by the letter "S," then the symbol for neutral species can be assumed as "NN."
Long-day species, by virtue of adaptation to environmental conditions, are long-day ones only in the first phase; in the second phase they are neutral ("LN"). Short-day species remain photoperiodically independent of length of day for the first phase; in the second phase, coming under the control of the environment, they are short-day ("NS"). Long,-short-day and short,-long-day species have followed the course of adaptation to the length of day still further: both phases of flowering are under the control of environment and are determined by the length of day. Consequently, long,-short-day species can be marked by letters "LS" and the short,-long-day species can be marked by the letters "SL" (Chailakhyan, 1969). The first phase of flowering in long,-short-day species proceeds only under a long day while in short,-long-day species this phase proceeds only under a short day. This is puzzling because the first phase of flowering is associated with the controlling action of a long day (in long-day species) or with control independent of the length of day (in short-day species).
Investigation of changes caused by age and of the juvenile stage of long,-short-day species enables us to draw certain conclusions about the two-phase photoperiodic control of the flowering of plants. It is known that the period of formation of the vegetative organs before the onset of flowering, or the period of the juvenile phase, fluctuates between a few days and a few months (Lang, 1965). The flowering response of long,-short-day Brynphyllum, which sets in at a successive replacing of long days by short days, occurs only in adult plants at the age of no less than one year with no less than 10-12 pairs of large well-developed leaves (Resende, 1952; Zeevart, 1962). Younger plants fail to flower under such a manipulation of the photoperiodic regime.
It is possible to reduce this long period of the juvenile phase by treating the plants with gibberellins. It was demonstrated that Bryophylium plants thus treated flower under constant short days (Biinsow and Harder, 1956; .Biinsow, Penner, and Harder, 1958). Subsequently it appeared that three-month-old plants flower as a result of treatment with gibberellin (Resende and Viana, 1959; Penner, 1960; Wadhi and Mohan Ram, 1967) .
In our experiments plantlets formed from adventitious foliar buds of Bryophyllunt daigremontianum initiated flower buds 50 days after spraying with gibberellin under short days. Young shoots formed from such buds that were still undetached from rooted leaves flowered under the same conditions (Chailakhyan, Yanina, Frolova, 1968, 1969).
If the period of the juvenile phase is shortened by gibberellin and the process of flowering sets in under the influence of short days, then according to Zeevart (Zeevart, 1969), Bryophyllum can be considered as a typical short-day species ("NS"). However, in contrast to short-day species in Bryophyllum and apparently in other long,-short-day species, the juvenile phase is con-trolled by the length of day and proceeds only under long days.
Similar data are absent for short,-long-day species (Scabiosa, Campanula, and Coreopsis) , but it is known that these species under short days are in the rosette or bush form and start to produce stems only when exposed to long days (Chouard, 1957; Wellensiek, 1960; Ketellapper and Barbaro, 1966). They may thus be considered typical long-day species ("LN"). But the juvenile phase in short,-long-day species in contrast to long-day species is controlled by the length of day and proceeds only under short days.
The juvenile phase in short- and long-day species of annual plants is independent of the length of day in spite of the fact that in certain forms, as in tobacco, the short-day Mammoth (N. tabacunt) and the long-day Sylvestris (N. sylvestris), the juvenile phase is of long duration (Yevtushenko, 1947). The photoperiodic response of long,-short-day and short,-long-day species is distinguished by the fact that their juvenile phase is also under the control of the environment. Long,-short-day species actually are short-day ones: in the first phase of flowering they are neutral and in the second phase they are short-day ones but their juvenile phase proceeds only under long days ("L-NS"). Long,-short-day species basically are long-day ones: in the first phase they are long-day species; in the second phase they are neutral and their juvenile phase proceeds only under short day ("S-IN").
The adaptive significance of controlling the juvenile phase by exposure to long days consists in the prevention of too-early flowering of young plants (Chailakhyan and Podolny, 1968). This phenomenon in long,-short-day species is seen in the fact that leafy plants with large stems are formed under long days prior to the conversion to flowering while in short,-long-day species it is seen that, prior to the conversion to flowering, vigorously tillering forms with numerous leaves and stems develop under short days.
The data on the relationship of the juvenile phase and the flowering phases, both controlled by the conditions of the length of day and independent of the latter in the plants of various photoperiodic groups, are summarized in Table 2.
Thus the flowering of plants of various photoperiodic groups falls under the controlling action of the length of day to a variable degree: in long- and short-day species
to a lesser extent while in long,-short-day and short,-longday species to a greater extent. The extent is determined by the adaptive function of photoperiodic response which permits the plant to flower at the most favorable age and season (Chailakhyan, 1958).
Control of the duration of the juvenile phase in plants occurs not only under the influence of the length of day but also of other environmental and internal factors. Here it is essential to point out that the passage of the juvenile phase in some short,-long-day species can be effected by exposing them to short days or by treatment with lower temperature (Lang, 1965). The juvenile phase of winter forms and biennials is controlled by lower temperature, and since they behave as typical long-day species in subsequent responses (Chailakhyan, 1942), they can be denoted as "T-LN." The juvenile phase of perennials, characterized by a significantly longer duration than in annuals, is controlled by changes caused by age and internal factors.
The Mystery of Plant Photoperiodism and the Outlook of Its Solution
Analysis of environmental factors and of the possible role of internal factors in the conversion of plants to flowering enables us to approach the solution of the mystery of photoperiodism in long- and short-day species.
Flowering as a main criterion of photoperiodism is entirely different for these two types. In long-day species flowering is reflected by the formation of flower-bearing stems under long days and is related to the production of gibberellins and other changes in metabolism. In short-day species flowering is reflected by flower initiation which proceeds under short days and is related to the production of substances of the anthesin type and other changes in metabolism (Table I ). The production of gibberellins and anthesins and the course of other biochemical processes related to the length of day are entirely the same in both types. The resulting effect, however, is different because in long-day species the genetically fixed ability to produce gibberellins was lost, and this loss
is balanced by the physiological process of their production under long days. The ability of producing substances of the anthesin type was lost in short-day species, and this loss is balanced by the physiological process of their production under short days. This phenomenon was demonstrated for long-day species (Lang, 1956, 1957; Marth, Audia, and Mitchell, 1956; Biinsow and Harder, 1956, 1957; Lona, 1956, .1957; Chouard, 1957, 1958; Chailakhyan, 1957, 1958, and others), for Iong,-short-day species (Biinsow, Penner, and Harder, 1958; Resende and Viana, 1959; Penner, 1960) as well as for short,-long-day speices (Chouard 1957; Ketellapper and Barbaro, 1966) by the insertion of gibberellins under the conditions of short days. Probably the loss of genetically fixed ability for intensive production of substances of the anthesin type in short-day (NS), long,-short-day (L-NS), and short,-long-day (S-LN) species under any length of day could also be substituted by the insertion of sub-stances of the anthesin type under the conditions of long days. However, such substances have not been isolated from plants, and conclusions about them are drawn on the basis of indirect biological responses.
The genetic information about the process of flowering in species that are neutral to the length of day is realized, regardless of, the length of day, directly through an internal hereditary program. The hereditary control of flowering which is independent of the length of day can be called autonomous control.
The genetic information about the process of flowering in species adapted to the length of day is also translated through an internal hereditary program while its direct realization is put under the control of an environmental factor, the length of day. This genetic control of flowering that was formed in the process of evolution can be called photoperiodic control (Table 3).
Therefore, as seen in Table 3, the properties controlled by daylength and those properties not under such control interact in various combinations with the photoperiodic phenomena and with the genetic complement of the plant. These properties do, however, change. If the production of floral_ hormones by day-neutral plants is under autonomous control, then as adaptation to daylength progresses, hormone production will increasingly come under photo-periodic control in the evolving long- and short-day plants. Ultimately, hormone production will be completely under photoperiodic control in long-short-day and short,-longday species.
The recognition of the role of factors related to both photoperiodic and autonomous control permits us to come closer to the solution of the main mystery of photoperiodism and to the analysis of the phenomenon as a whole. Two trends in further investigations appear. First, the identification and description of the mechanism of action of hormonal factors in various phases of conversion of plants from vegetative growth to flowering in connection with photoperiodism and other adaptive responses as well as changes in plants caused by their age. Secondly, the identification and description of the mechanism of the realization of genetic information that determines the flowering of plants by using the outstanding progress achieved in studying the heredity of plants (Bonner, 1968) and in connection with investigations on hybridization of long- and short-day species as well as other ecotypes that sharply differ in the dates of flowering (Herer, 1950; Naylor, 1953; Bremer, 1961; Griesel, 1966), on polyploidy (Konstantinov and Zhebrak, 1963) ; and on plant mutagenesis.
Investigations in these two directions bound by a common and single goal seem to be the most promising and would be able to initiate a new semicentennial history in the study of photoperiodism.
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Botany Is Not Dead—It's Still Sleeping1
Elwood B, Ehele
Hark! The jolly green giant mutters in his sleep. When William Stern's Quo Vadis Botanicum? crossed my desk
1 The title and the paragraphs that follow it are offered as one man's opinion and should not be construed as representing the opinions of his employer.
I knew it would be followed by a series of remarks like those in the December issue of Plant Science Bulletin. Having been a botanist all my professional life, I was all too familiar with that type of wailing. It's almost diagnostic of a botanist that he blames his second-class citizen-ship on almost everyone but himself. Blame the trend toward integrated biology departments. Blame CUEBS for its concept of a core curriculum for all of the biological sciences. Blame the AIBS for succeeding at bringing some order into the organizational chaos of the American Biological Community. When all else fails, blame the unenlightened administration. There are plenty of targets. Have at it. Play Don Quixote while the giant sleeps on.
The real reason for our dilemma was much more accurately described by jack Sharp during a recent visit to AIBS. The plain fact is that botanists have failed miserably at convincing the public or even the hordes of students they process that plants are important, that plants hold the sine qua non of survival, and that botany is where much of the action must be if man is to share in this survival. Yes, the plain fact is that botanists, you and I, have failed. It's not really surprising, however, when you see the way we have strutted around uttering statements about the importance of botany which were supposed to be true simply because we said them. Plants are important, there is no argument on that. It remains to be seen whether botanists will be.
Arthur Galston's otherwise fine article (Plant Science Bulletin 16(1) :1-7) seems to miss the main point when he says,
... I think the first thing we need to tell our young friends who are challenging us to climb down out of the ivory tower into the cobblestone strewn streets is 'Fine, we will send you a delegation; but some will have to stay up here to keep the store running.'
The delegation (or is it relegation) should be to the tower not the streets. If we botanists don't get our people into the streets to learn how to get their hands on the levers of social change and political responsiveness we will see continuing reduction of support for those few creative hothouse flowers who should remain in the tower, if indeed by some cultural accident the tower is left standing. Whether the omniscient "we" in the above quote are really able to "tell our young friends" anything remains to be seen. We may be beyond telling them anything; we may have to show them. If all we can show them is a delegation, it had better be a darned large one. They (the students, the people) have been put-off and put-down by the tower and its self-serving rhetoric far too often. They aren't going to stand for much more of it. When Galston indicates that he believes in "the collective wisdom of the people of a democracy to decide important matters concerning their own fate" he gets at the real problem. The "collective wisdom" is rapidly reducing budgets and increasing its call for relevant performance with the little money that can be spared from the higher priority jobs we have too long ignored while strutting around in our towers. We had better come down from our. "ego trip" and get to work—real work. Or is it all just a dream?
What has the giant done to bring on his present ap-
parent stupor? For years he's cranked out papers in his pct esoteric area with one hand and graduate students with the other while the real world was falling apart at the seams. Scan the last few issues of most botanical journals and see how much you find that is really relevant to the salvation of the planet and the unfinished business of mankind. Sure, there will be a few papers scattered here and there that have relevance to real problems but they will likely be obscured by great masses of pap on The Research I Did Last Summer," The Cartwheels My Students Will Turn In Order To Get Their Degrees," or worst of all, "I Just Kept Turning The Same Old Crank And This Is What Came Out." Please don't misunderstand, the problem isn't with the journals, it's with the heads of the botanists who will feed and put up with this sort of stuff—they're still sleeping.
I cheered when I heard Arthur Cronquist present a resolution before an AIBS Governing Board Study group to the effect that the most important concept we must impart to our students is that of spaceship Earth with its finite resources, limited channels for the recycling of materials, and serious people pollution problems. On the 26 campuses I've visited this year and last, I have not seen too much of that going on. The green giant is still hung up in the plurilocular zoosporangia of Ectocarpus, the intercalary meristems of one grass or another, or trying to get the correct number of carbon atoms in ATP while begrudgingly putting it on the blackboard. All of these things and many more can be relevant. As dealt with, however, in most research and teaching, they simply aren't.
Ifs time we realize that the research we do should be related to, if not aimed at, real problems rather than our esoteric whims. The evidence is in. The world at large and our students in particular have tuned us out. There is an amazing amount of brain power in the botanical community. Every bit of it is critically needed. Let the doubters look at the report by Steinhart and Cherniak issued by the Executive Office of the President under the title "The Universities and Environmental Education," or chew on the 1968 words of the then U.S. Commissioner of Education, Harold Howe, who said, "Entirely too many professors in graduate schools are interested only in the kind of teaching which produces more professors in graduate schools."
Now, it happens that there are botanists in graduate schools and elsewhere fighting to prevent more Lake Erie messes; there are botanists researching perilously important questions; and there are botanists telling it like it is to their students. It's too bad they are so few in number that they constitute the exception rather than the rule.
But, hark, the green giant is muttering! He is still asleep to be sure, but there are signs of hope all around that one day soon he will wake up and take hold. It isn't necessary to play at blaming everyone and everything else for his long sleep. It is necessary to accept the blame ourselves and make a renewed commitment to make our individual lives count in the battle for survival, growth, and enlightenment. Botanists could become important yet!
NOTES FROM THE EDITOR
I am pleased to announce that Dr. Robert W. Long, Professor of Botany and Chairman of the Department of Botany and Bacteriology of the University of Southern Florida, Tampa, has accepted appointment as the new Editor of the Plant Science Bulletin. Dr. Long will begin his five-year term with Volume 17, the first number of which will appear early in 1971.
Corrigenda: In the article "Terminology in the Plant Sciences" by W. C. Baum (Plant Science Bulletin 16, No. 2), the term pantonenaatic should have appeared at the end of the sentence on page 3, as follows: "3) flagella bearing lateral appendages: pantonematic." Both J. L. Strother and W. C. Steere have called attention to the fact that the term infructescence as used in the article was misspelled.
NEWS AND NOTES
1971 Botanical Society Meeting
This advance information is being provided so that you may begin making your plans for the coming year. More detailed information is being prepared for our December issue. In place of our usual late August meeting in association with other AIBS societies, the Botanical Society of America will hold its annual meeting in June, 1971 in collaboration with the Canadian Botanical Association. General arrangements, however, will be handled by the AIBS. The following outline has been provided by Dr. S. N. Postlethwait, our Program Chairman:
Theme: Our Northern Plants: Their Importance in the World's Resources
Place: University of Alberta, Edmonton, Alberta Time: June 20-24, 1971
Local Chairman: Wilson Stewart
Department of Botany
University of Alberta
Edmonton, Alberta, Canada Probable deadlines:
Member $12.00 $15.00
Spouse 3.00 3.00
Student 5.00 8.00
Botanic Gardens at Bogor Damaged by a Hurricane
A freak hurricane on January 4, 1970 resulted in extensive damage to one of the worlds' leading botanical establishments. The loss to botany of such a famous and important collection transcends national boundaries and
it is felt that many of the institutions and individuals who have benefited from the Gardens and its associated facilities such as the Treub Laboratory and the Herbarium Bogoriense may wish to do something tangible to help.
University of Wyoming Offers Ph.D. in Botany
At its regular August meeting, the Board of Trustees of the University of Wyoming approved a Ph.D. program for the Department of Botany. Although the Rocky Mountain Herbarium is recognized nationally and inter-nationally and a number of well-known botanists have earned masters' degrees at Wyoming, the Ph.D. has never been offered. Recently the faculty has been expanded to six full-time members, and another appointment is anticipated for the 1971-72 academic year. With the opportunity to pursue studies leading to the doctorate, students with an interest in the area of environmental and evolutionary botany should find Wyoming even more attractive. Recently remodeled laboratories and new equipment pro-vide additional facilities for chemotaxonomic and biosystematic research. For additional information, write: Dr. John R. Reeder, Head; Department of Botany; University of Wyoming; Laramie, Wyoming 82070.
Major Evolutionary Events Symposium
On page 6 of our June issue a preliminary announcement concerning publication of the proceedings of this symposium appeared. The latest and more complete information is the following:
The Cambridge Philosophical Society is publishing, as Vol. 45, No. 3 of Biological Reviews, the Symposium on "Major Evolutionary Events and the Geological Record of Plants" presented at the XI International Botanical Congress, Seattle, Washington, U.S.A., in September, 1969 under the Chairmanship of Professor Harlan P. Banks. The Symposium is a summary of major events during a three-billion-year span and will be of interest to a variety of readers. The separate papers are as follows:
H. P. Banks—Introduction.
J. W. Schopf—Precambrian microorganisms and evolutionary events prior to the origin of vascular plants.
W. G. Chaloner—The rise of the first land plants.
C. B. Beck—The appearance of gymnospermous structure.
J. Pettitt—Heterospory and the rise of the seed habit.
J. Muller—Palynological evidence on early differentiation of angiosperms.
H. P. Banks—Summary and time scale.
The Symposium will be sold at the normal price of single issues of Biological Reviews, :£2.12.6 (S8.00). This issue may be purchased through a bookseller or through the American Branch of Cambridge University Press, 32 E. 57th Street, New York 11022.
Dr. Otto Stein, Head of the Department of Botany at the University of Massachusetts, announces the following
changes in his department: Albert C. Smith, formerly Wilder Professor at the University of Hawaii, has been appointed as Ray Ethan Torrey Professor of Botany: Paul J. Godfrey, formerly at Cape Lookout National Seashore, Beaumont, North Carolina, has been appointed an Assist-ant Professor in the Department, as have Livija Raudzens, formerly at Columbia University, and Peter L. Webster, formerly at Brookhaven National Laboratories. John L. Harper, Head of the School of Plant Biology of the University College of North Wales, and D. Ross Moir of Branton University, Branton, Manitoba will be Visiting Professors. Professor S. Shapiro will be on sabbatical leave to work at Wageningen in the Netherlands.
Dr. V. Raghavan, who has been at the University of Malaya, Kuala Lumpur, for the past few years, will join the Academic Faculty of Botany, College of Biological Sciences, Ohio State University, Columbus, as of the fall of 1970.
Paul D. Voth became Professor Emeritus of Biology at the University of Chicago in 1970. Dr. Voth will now be associated with the Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois.
Erik K. Bonde of the University of Colorado has been named a visiting scientist to Rumania under the U.S. National Academy of Sciences' Scientific Exchange Pro-gram. Dr. Bonde is interested especially in Rumanian botanical studies of Carpathian Mountain alpine regions, in relation to his Colorado Rocky Mountain research on the growth and development of alpine plants.
Dr. William H. Matchett, formerly of the Battelle Seattle Research Center, has been appointed Professor of Botany at Washington State University, and replaces Adolph Hecht as Chairman of the Department of Botany. After 15 years as departmental chairman, Hecht will continue as Professor of Botany and Genetics. Dr. Joseph L. Hindman, formerly of the Department of Botany at the University of Georgia, has been appointed Chairman of the Program in General Biology and Associate Professor of Botany at Washington State. Dr. James C. Hickman, Assistant Professor of Botany and General Biology, has resigned to accept a position at Swarthmore College.
Dr. Sterling B. Hendricks, research scientist with the U.S. Department of Agriculture for more than 40 years, retired on July 3], 1970. Dr. Hendricks is best known for his pioneering work in photoperiodism, and recently for his and his associates' discovery and isolation of phytochrome, the protein molecule that regulates many plant growth processes. Among the many awards that have been granted in recognition of Dr. Hendricks' achievements are the Hillebrand Prize, the Science Award of the Washington Academy of Sciences, the Day Medal, USDA's Distinguished Service Award, the first Presidential Award for Distinguished Civilian Service, the first Rockefeller Public Service Award, the Hoblitzelle Award in Agricultural Sciences (with H. A. Borthwick), the Stephen Hales Award (with H. A. Borthwick), the Distinguished Service Award of California Institute of Technology, three honorary degrees, presidencies of several professional societies, and membership in the National Academy of Sciences.
George Neville Jones 1904-1970
George Neville Jones, professor of botany and curator of the Herbarium at the University of Illinois, died June 25 at the age of 66. He never recovered from injuries received in an automobile accident on April 14, 1968, while enroute to Allerton Park where he had collected plants for two decades.
His numerous publications include the books, "Vascular Plants of Illinois," "Flora of Illinois," "Annotated Bibliography of Mexican Ferns," and "Taxonomy of the American Species of Linden."
Born January 26, 1904, in Boston, England, he moved to the United States with his parents. He received his BS degree from the State College of Washington, Pullman, in 1930, and his MS and Ph.D. from the University of Washington, Seattle, 'in 1932 and 1937. From 1937 to 1939 he was on the faculty at Harvard University as instructor in biology, tutor in the division of biology, and technical assistant in the Arnold Arboretum. He came to Illinois in 1939.
In 1967, Dr. Jones received the Eunice Rockwell Obberly Award from the American Library Association for his "Annotated Bibliography of Mexican Ferns," judged the best bibliography in the field of agriculture or related sciences. He was a Guggenheim Fellow in 1944, a visiting lecturer at the University of Wisconsin in 1947, and a visiting lecturer at the University of Colorado in the summers of 1960 through 1965. From 1944 through 1961, he was editor and reviewer for the American Mid-land Naturalist.
Jones was a member of the New England Botanical Club, American Association for the Advancement of Science, Botanical Society of America, American Association of University Professors, American Biological and Lichenological Society, American Society for Plant Taxonomy, Sociedad Botanical de Mexico, Illinois State Academy of Science, American Fern Society, Sigma Xi, California Botanical Society, International Association for Plant Taxonomy, and Indiana Academy of Science.
Loren Clifford Petry 1887-1970
The death of Loren Clifford Perry, professor of botany, emeritus, on May 4 ended the career of an outstanding student and teacher of botany. Not only was Dr. Petry renowned as a teacher of introductory botany to thousands of students at Cornell but his dedication and vitality became equally famed during his retirement years on Cape Cod.
Petry was born of Quaker parentage in New Paris, Ohio. His first interest was engineering and his B.S. from Earlham College in 1907 was taken in that field. A year later he earned a second B.S. at Haverford College. During the following two years he taught science in the high school at Urbana, Ohio. On the advice of another noted teacher of botany, Millard Markle of Earlham, he decided to 'further his interest in plants by pursuing graduate studies in botany at the University of Chicago. There he earned the M.S. in 1911 and the Ph.D. in 1913.
Petry's first post was an Instructorship at Syracuse in 1914. He was raised to Assistant Professor in 1916 and Associate Professor in 1919. From 1922 to 1924 he was on leave from Syracuse as Acting Assistant Professor of Botany at Cornell. During the years 1919 to 1925 he served as Director of Summer Session at Syracuse. In 1925, he was appointed Professor of Botany at Cornell where he remained until his retirement in 1955.
Particularly valuable was his effectiveness in the teaching of introductory botany. An inveterate traveller and observer of all aspects of the environment, he felt that facts should be used as tools in the solution of problems rather than as things to be memorized and stored away. As a result, his lectures emphasized ways of learning and using rather than memorizing. His students were encouraged to think. Two tangible results of this attitude were a laboratory manual for introductory botany written in collaboration with E. M. Palmquist and a "Keys to Spring Plants" written in collaboration with W. C. Muenscher. Approximately 12,000 students were exposed to his botanical wisdom during the 30-year span of his teaching at Cornell.
Petry's research interest centered around the first plants to occupy dry land (Devonian period). His early collecting expeditions to the Gaspe Peninsula resulted in a splendid collection of Devonian plants at Cornell that has been increased by his students until it is now one of the best in the world. His enthusiasm led others to this area of study and the plants of this period have now become a critical item in studies of plant evolution. Petry's enthusiasm for paleobotany also led him and Ralph Chaney of Berkeley to found in the Iate thirties a paleobotanical section of the Botanical Society of America. Petry served as the second chairman of this group (1938).
Loren Petry served botany also through participation in its national organization, the Botanical Society of America. In 1933 he was elected to be its Secretary for a three-year term. In 1937 he was elected Vice-President of the Society. From 1936-1939 he was a member of the Society's Committee on Education where he was instrumental in the production of two publications "An Exploratory Study of the Teaching of Botany in the Colleges and Universities of the United States" and "Achievement Tests in Relation to Teaching Objectives in General College Botany." Both of these reflected some of his own philosophy in teaching.
The extent of Dr. Petry's dedication to observation, to interpretation, and to teaching can be measured by his activity in the fifteen-year period following his retirement in 1955.
He taught for various periods at the University of Missouri, Hofstra College, University of Utah, and Welles-Iey College. He was also a member of a national panel of lecturers sponsored by the American Institute of Biological Sciences. In 1960 he moved permanently to Cape Cod and continued to lecture locally and abroad, one series at The University, Reading, England.
On Cape Cod he became associated with the Cape Cod Museum of Natural History, Brewster, Massachusetts for which he led trips for young and old to view geological phenomena, salt marsh plants, and wildlife in general. He cut and marked nature trails. He lectured on a range of topics from edible mushrooms to salt marsh plants to
the glaciation of New England. He devised exhibits and experiments to attract and to explain.
It was no surprise that in 1966 his Alma Mater, Earl-ham College, rewarded him with an honorary D.Sc. nor that he was immensely pleased to be presented for that degree by the late Millard Markle who had originally influenced him to go on to graduate work at Chicago.
Harlan P. Banks
TSCHUDY, R. H., AND R. A. SCOTT (Editors). Aspects of Palynology. John Wiley & Sons, Inc., New York, 1969. vii + 510 pages. $24.95.
The science of pollen analysis is relatively new, yet it already has achieved an important role in the study of such diverse disciplines—to mention only a few—as paleoecology, archaeology, paleobotany, and petroleum geology. During the past several decades the recognized importance and application of palynological research has resulted in a large body of published data, little of which appears in the form of syntheses or comprehensive reports. As stated by the editors, R. H. Tschudy and R. A. Scott, Aspects of Palynology is designed to provide just such syntheses to the beginning palynology student, teacher, and researcher through a collection of articles on the nature, scope and applications of the study of fossil pollen and spores.
This book presents a collaborative effort by 14 separate authors. The first five chapters provide a general background of data essential to the understanding and study of fossil pollen and spores. Represented in these chapters is an introduction, followed by discussions of pollen/spore classification and descriptive teminology by R. H. Tschudy, pollen ontogeny and pollen wall development by A. O. Dahl, systematic and nomenclature guide-lines used in palynology by J. M. Schopf, and a section on the relationship of sedimentation to palynomorph preservation by R. H. Tschudy. The next two chapters of the book cover subjects pertaining to pollen analytical interpretations. The first of these, by J. W. Funkhouscr, examines the reliability of pollen samples and provides a useful summary of frequent sources of contamination during the collection and subsequent pollen analysis of sediments. The second of these two chapters, by R. H. Tschudy, is devoted to a summary of the major concepts around which pollen analytical interpretations are based. The remainder of the book, except for one chapter by W. R. Evitt on non-palynomorphs often encountered in pollen preparations, contains a series of chapters devoted to a brief summary of palynomorph assemblages through geologic time. These include discussions of Precambrian and Early Paleozoic palynomorphs by J. M. Schopf, Devonian spores by J. B. Richardson, Mississippian and Pennsylvanian microfossils by R. M. Kosanke, Permian palynomorphs by G. F. Harr, Triassic spores and pollen by W. G. Chaloner, Jurassic and Early Cretaceous micro-fossils by N. F. Hughes, Late Cretaceous and Early Tertiary palynomorphs by J. S. Penny, and Late Cenozoic palynology by E. B. Leopold.
Except for its expense, Aspects of Palynology is well suited for use as a college textbook or as a reference source. The chapters are arranged in a logical chronological sequence, and in most cases they are well illustrated (except on page 352 where part of one illustration is faded and illegible) and contain sufficient bibliographies. However, there are a few disconcerting instances in which important literature either was not mentioned or was cited incorrectly. In chapters dealing with the relation-ships of palynomorphs to sedimentation and factors that affect reliability of samples, neither of the authors (R. H. Tschudy nor J. W. Funkhouser) cites or mentions the contributions of G. W. Dimbleby (1957) on pollen preservation and palynomorph movement in terrestrial soils, S. Goldstein (1960) and W. C. Elsik (1966) on biologic degradation of pollen and spores, A. G. Sangster and H. M. Dale (1961, 1964) on differential pollen preservation in lacustrine and bog deposits, H. Tauber (1965) on differential pollen dispersion, and E. J. Cushing (1967) on differential pollen preservation. In several instances references cited in the text either do not agree with, or are omitted from, the references cited in the bibliography. Some examples include: references cited on page 35 include (Michel, 1940) and (Freytag, 1954) yet in the bibliography they appear as (Michel, 1950) and Freytag, 1964) ; on page 141 a reference is listed as (Gothan and Weyland, 1964), yet in the bibliography it is listed as (Gothan and Weyland, 1954); on page 319 a reference is listed as (Seward, 1904) yet it does not appear in the bibliography; and on page 326 (Erdtman, 1948) is cited, yet omitted from the bibliography.
More than three-fourths of this book is devoted primarily to the pollen record of the Pre-Quaternary portion of the geologic record and thus will undoubtedly and logically be utilized most widely for studies of Pre-Quaternary palynology. Yet this book should also be of interest to Quaternary palynologists since there are useful chapters on applied palynology, pollen ontogeny, Late Cenozoic palynology, and non-palynomorph microfossils encountered in palynological samples. The merits of this book outweigh its minor faults and in spite of its initial expense, it should provide a useful reference source for many years.
Vaughn M. Bryant, Jr.
Effects of Pesticides on Fruit and Vegetable Physiology. National Academy of Sciences, Principles of Plant and Animal Pest Control. Vol. 6. Washington, D.C. 1968. 90 pages. $3.25 + .20 handling.
The volume does an excellent job of bringing the botanist into contact with literature on growth regulators in a field esoteric even to most physiologists. In nearly every chapter, the authors conclude that there is an acute need for more careful and thorough investigation. Those who look for an understanding of mode of action will be disappointed. Rather, this is a compendium of who, what, when, and where with relatively little "how." Fruits obviously offer some unique opportunities for research with aging and senescence at least partially delimited by the climacteric. The book does a good job, so far as I can tell, of discussing current research and problems in this interesting area.
T. J. Muzik
HYAMS, E. AND W. MACQUITTY. Great Botanical Gardens of the World. Macmillan, New York, 1969. 288 pages. S35.00.
If, like the reviewer, you have been delighted by visits to some of the world's leading botanical gardens, perusal of this magnificent volume will bring back many pleasant memories as well as to whet your appetite for travel to see gardens you may have missed. In his foreword to this volume, Sir George Taylor, Director of the Royal Botanic Gardens at Kew, has written. "but no work known to me deals with the major botanical gardens of the world with the scope and on the lavish scale of Great Botanical Gardens of the World. The author, Edward Hyams, and the photographer, William MacQuitty, have chosen a broad canvas on which to present their facts and impressions of their gardening odyssey." Of the 42 botanical gardens listed by name in the table of contents, 18 are in Europe, 8 in North America, 5 in the USSR, 6 in the "tropics," and 5 are listed as "southern hemisphere." A separate section is devoted to several gardens in japan. At the end of the book, and after the detailed index, are five pages on which 525 of the world's botanical gardens, compiled from the International Directory of Botanical Gardens (Utrecht, 1963), arc identified and located by corresponding numbers on accompanying maps. A minor error involves a picture on page 97, labeled as a view of SchOnbrunn park, but actually a view at Belvedere park, also in Vienna. Botanist-gardners who are also interested in photography will be pleased to note the Technical Data on cameras, lenses, etc. (page 13). In addition to the many excellent black-and-white photographs, 64 of the pages are in brilliantly reproduced color.
NUMATA, M. AND S. ASANO. Biological Flora of Japan, Vol, 1. Sympetalae—1 -f- Introductory Volume. Tsukyi Shokan Publ. Co. Ltd. Tokyo, 1969.
This work is an ambitious undertaking to represent by line drawing, photograph, and terse statements the ecological status of (all?) the native and introduced plants of Japan. Volume I (of a projected five volumes) covers largely composites and a few others of the Sympetalae. The basic format of the first volume is a devotion of two pages to each species selected by the authors. The lefthand side consists of terse statements in Japanese and English on habitat including distribution, climate, soil, physiography, and vegetation type; and then life-form including dormancy, dispersal unit, and other ecological features, together with a photograph of the plant in some habitat situation. The righthand side of the pair of pages illustrates in excellent line drawings the plant in question. The first volume was distributed in a handsome box together with a hardbound volume of introduction. The introduction is also bilingual and briefly explains the in-tent of the work and the bases on which the terse eco-Iogical notes are made. As a work of art, the present volumes represent a real triumph. Both the photographs and the drawings are well executed, although I am taken a bit aback at the rather overpowering exhibitions of the underground portions of a plant—masses of roots which don't seem to tell too much.
But when I ask the question, "What scientific function does this work fill?" I am less easily convinced of its great worth and significance. To my mind a biological flora is one in which a great deal of ecological life history data are accumulated for each taxon in a regional flora. The model for such biological flora is probably the long-term publication of ecological life histories in the British Journal of Ecology. The present work does not measure up in terms of in-depth studies to this extent. Habitat features and life-form descriptions are so terse as to be much too general. However, the work should be valuable as a guide to ecological interpretations of the Japanese flora. Certainly plant ecologists working on specific communities would want to compare their own evaluations with the summary notations given in the present work. And as a device for corroborating identification, the work should be eminently useful, especially with the habitat photographs and the derailed line drawings.
The primary value of this series to botanists other than those in Japan would be: (1) to have a pictorial reference for validating plants collected in Japan or known to be of Japanese origin; and (2) to serve as a model with modifications for other so-called biological floras whose intent is to describe the habitat features of the members of the regional flora.
A. R. Kruckeberg
DAVIS, P. H. Flora of Turkey and the East Aegean Islands. Edited by P. H. Davis, assisted by D. P. Chamberlain and Victoria A. Matthews, University of Edinburgh. Volume three, Edinburgh, at the University Press, 1970; xvii, 628 pages, 15 full-page line illustrations, 98 maps. Price 9 pounds, 9 shillings. North American agent, Aldine Publishing Company, 526 South Wabash Avenue, Chicago 60605. U.S. Price $33.50.
This volume, devoted entirely to the large family Leguminosae, has been produced with the high standards set in Volumes 1 and 2, the latter of which was reviewed in this Bulletin in December 1968. A simplified terminology for summarizing internal distribution, similar to that used in Volume 1, has been adopted in preference to that of using solely the names of the Turkish vilayets. Contrary to earlier practice, new scientific names and new combinations are published in the text. Much of the text (including the largest genus, Astragalus, with 372 species) has been contributed by the research assistants, Dr. Chamberlain and Miss Matthews. As in earlier parts of the flora, treatments of certain genera or parts of genera have been contributed by specialists in these groups.
The Leguminosac is a very large and diverse family in this part of the world, and American botanists will find much of interest in the genera that are known chiefly because of a few introduced species. The number of native and introduced genera in the Turkish flora is not particularly large (68), but several genera are rep-resented by numerous species, as Trifolium with about 100, Vicia and Lathyrus with almost 60 each, Trigonella with 49, Onobrychis 46 and Medicago 30.
The contents of Volumes 4 and 5 have been announced by the Editor, and it is hoped that their production can be achieved as promptly as that of the present installment in this very useful and important series.