Plant Science Bulletin archive
Issue: 1960 v6 No 5
PLANT SCIENCE BULLETIN
A Publication of the Botanical Society of America, Inc.
VOLUME 6 DECEMBER 1960 NUMBER 5
More About the Origin of Vascular Plants'
BY WILSON N. STEWART
University of Illinois
For the past five years I have become increasingly perplexed by the frequency of articles supporting the claim that vascular plants with lycopsid affinities occurred in the Cambrian. If the evidence justified the conclusion, then this would be one of the most spectacular paleobotanical finds since Lang and Cookson's (1935) discovery of bona fide vascular plants in the Silurian rocks of Australia. Far more important than the spectacular nature of such discoveries, are the effects they have had on interpretations of origins for vascular plants. If we agree that relatively highly evolved vascular plants existed in Cambrian times we must consider the possibility that they originated from some group other than Upper Silurian and Devonian psilophytes of the Rhynia-type. In agreeing to this premise, we at the same time accede to the argument that vascular plants may have had an origin from more than one as yet unknown groups of ancestors. Because of the impetus given to the idea of polyphylesis for the origin of vascular plants by the discovery of plant remains in Cambrian deposits, I believe it is important that we consider the supporting evidence more critically and, having done this, evaluate how our conclusions about vascular plant origins are to be reflected in a system of classification.
To do this we must review briefly the state of evidence related to origins shortly after 1921 when Kidston and Lang had completed their papers describing the Middle Devonian flora of the Old Red Sandstone. Around 1840, long before Mackie picked up the first specimen of the famous chert, Hofmeister and later Lignier, among others, speculated about the nature of ancestral vascular plants. In general, their speculations led to the conclusion that primitive vascular plants consisted of three dimensional dichotomizing axes showing little organ differentiation and with terminal sporangia; thus during the course of evolution these axes were variously modified to give rise to plants with differentiated organs.
With the discovery of Rhynia and Horneophyton by Kidston and Lang and the rediscovery of Psilophyton, the idea was soon widely adopted that here, in fact, were primitive vascular plants of the type already postulated. To make the evidence of common ancestral origin for vascular plants even more convincing, supposedly transitional forms now placed in the Hyeniales, Protopteridales, and Protolepidodendrales were soon added. The logical
Modification of paper presented at IX International Botanical Congress Montreal, Canada, 1959. outcome of these events was the establishment of a single phylum for vascular plants—the Stelophyta proposed in 1931 by Pia and the Tracheophyta used by Sinnott in 1935. With the wide acceptance by morphologists of the Tracheophyta as a natural group of plants the monophyletic interpretation for the origin of vascular plants seemed to be established. Today, however, it is safe to say that the Tracheophyta is far from being assured a permanent position in a phyletic classification. The reason for this is directly or indirectly the result of investigations by Leclercq, Andrews, Banks, Hoskins and Cross, Read, Harris, Naumova, Kryshtofovich, Gosh and Bose, Kr~usel and Weyland, Arnold, Lang and Cookson, Dorf, Teichert and Schopf, Halle, Radforth and many others. Each has made a contribution to our knowledge of Devonian, Silurian or Cambrian floras since the time of Kidston and Lang's work on the Rhynie chert. The principle results of their investigations of these ancient floras are:
I) The Middle and Upper Devonian floras are heterogeneous being composed of numerous species, some of which are highly differentiated and can not be assigned to the Psilophytales.
Good summaries describing the heterogeneity of Devonian floras have been prepared by Leclercq (1954) and Andrews (1956). More than any other, Andrews supports the thesis that heterogeneity, per se, can be construed as evidence for the polyphyletic origin of land plants from unknown algal groups. This is made clear in his statement, —"The early land plants (excluding clearly defined representatives of the lycopods or articulates) presents a highly complex assemblage; some may be justifiably classified as psilophytes while others do not fit with any degree of comfort into any major category and seem to imply a highly polyphyletic origin from the algae."
To support this point of view, Andrews makes extensive use of evidence provided by I) structural differences between Devonian monostelic and polvstelic "stem" genera, and 2) the genus Crocalophyton, an Upper Devonian fossil described in an earlier part of his 1956 paper. In 1949 and
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MORE ABOUT THE ORIGIN OF
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subsequently Zimmermann noted the relatively high percentage of polystelic axes to be found among Devonian fossils and showed that with decrease in geological age there was a decrease in the number of polystelic forms. To ac-count for this phenomenon Zimmermann, in explaining the telome concept, suggests that the evolutionary process of syngenesis has occurred resulting in tangential fusion of many monostelic axes and that this process of fusion ultimately extended to the polysteles resulting in their tangential fusion and the formation of monostelic vascular systems. In his 1956 and later papers, Andrews seems to have over-looked this possibility. He states in his 1956 paper, "The contrast between plants of this sort (polystelic Steloxylon and Xenocladia) and those possessing slender monstelic stems (Rhynia and Asteroxylon) presents a deep and broad chasm to be spanned by an evolutionary bridge." That this chasm is neither deep nor broad is pretty well attested to by the inclusion in the same order, Pteridospermales, of both monostelic lyginopterids and polystelic medullosas. Furthermore, it appears from the researches of Delevoryas (1955) on the medullosae that syngenesis of axes and their vascular systems occurred in exactly the way postulated by Zimmermann. That tangential fusion of axes is not of uncommon occurrence in the plant kingdom is revealed by the thalli of certain green, brown and red algae composed of fused filaments; the fruiting bodies of many fungi composed of interwoven and fused hyphae; the axes of several ferns with false stems composed of tangentially inter-woven adventitious roots and true stems, and the tangentially fused parts of cones and flowers. In view of the wide-spread occurrence of syngenesis in the plant kingdom one
very logical and simple explanation of the heterogeneous Devonian floras represented in part by polystelic axes, is that they are the products of fusion of more primitive, monostelic axes of the Rhynia-type. The evidence from the medullosae favors this interpretation.
As noted earlier, a new genus Crocalophyton is the principal subject of the 1956 paper by Andrews and Alt. This genus, as its name suggests, is portrayed by the authors as a primitive shore-dwelling organism which can't be as-signed to any living or fossil group—an organism which is one representative of many different kinds that made an "effort" to evolve a vascular flora. Because of the obvious implication that Crocalophyton provides additional evidence supporting a polyphyletic origin of vascular plants from algal ancestors, this paper has received more than casual scrutiny. In brief, the results of these more critical reviews agree that this genus can be interpreted logically in another way. According to Andrew's interpretation much emphasis must be placed on the orientation of the two conical specimens which are described. If the broad portion of the specimen is considered to be the base and the more pointed portion the apex then the histology from base to apex consists of alternating areas of parenchyma and "strands." The latter are composed of horizontally directed cells whose radial walls show rather regularly arranged circular pits but showing no borders. Interpreted in this position Crocalophyton is, indeed, an unusual plant without extinct or extant equivalents. There is, as I'm sure we must agree, no good reason to assume that the more pointed end of a fossil specimen must represent the apex of an organism. Weathering has the disconcerting effect of shaping fossils so that they are conical, yet the specimen may turn out to be the root mantle of a fern stem which is in no way related to the plant's apex.
By turning the conical specimens of Crocalophyton on their sides, i.e., tipping them 900 so that their flat sides are horizontal instead of vertical, they can then be interpreted as wedge-shaped segments, weathered and broken from a cylindrical, trunk-like axis. Accordingly, the pointed end of a wedge represents the more nearly central parts of the axis and the broad "basal" face the more peripheral portions. By making this reorientation of the specimen the following rather simple interpretations are possible: 1) The wedge-shaped segments are from the trunk-like axis of a polycyclic portion of a vascular plant. 2) the "strands," alternating with layers of parenchyma, can now be interpreted as arcs of concentric bands of loosely arranged vascular tissue interspersed with very broad rays. 3) Instead of having an horizontal orientation, the pitted elements of the "strands" have the usual vertical orientation of tracheids with pits on their radial walls. The pits probably lack borders because of changes due to preservation of the cell wall.
The stem type having the features just listed is not uncommon among vascular plants where it occurs in the Medullosaceae and Cycadoxyleae. It has been observed by Delevoryas that a specimen of Crocalophyton would bear a striking resemblance to a wedge shaped segment of Ptycho-
xylon Levyi, a member of the Cycadoxyleae. This does not mean that Crocalophyton is a member of that family. What it does mean is that Crocalophyton can logically be interpreted as a vascular plant with gymnosperm affinities. Until this possibility is investigated further it is my opinion that we can hardly accept Crocalophyton as providing evidence supporting a polyphyletic origin for vascular plants.
The second point I want to consider is well put in the title of Leclercq's 1954 article, "Are the Psilophytales a Starting or Resulting Point?" From the time the lycopsid genus Baragwanathia was described from Silurian deposits by Lang and Cookson (1935) it has become increasingly apparent that Middle Devonian psilophytes (sensu Kidston and Lang, 1917-1921) can not be construced as the progenitors of all vascular plants. There can be no question that we must abandon the idea that the Middle Devonian genera Rhynia, Psilophyton, and Horneophyton themselves provided the stock from which sphenopsids, lycopsids, and probably pteropsids subsequently evolved. There is now convincing evidence that the Sphenopsida, represented by Protohyenia, are to be found in Lower Devonian deposits. This places the beginnings of at least two evolutionary lines of vascular plants, the Sphenopsida and Lycopsida, at an earlier time than Middle Devonian Psilopsida. It has been suggested that the lycopsid line may extend back to the Cambrian. With the possible exception of the Middle Cambrian lycopod flora described by Kryshtofovich (1953), it is interesting to note that every new Lower Devonian or Silurian vascular plant flora that is described contains elements which can be assigned to the Psilophytales in the restricted sense. In other words the age of psilophytes has also been pushed back into the Silurian. As long as the primitive Rhynia-type is found to coexist with other kinds of vascular plants, as they do in the Upper Silurian, then the thesis that the Rhynia-type provided the ancestral stock for lycopsids, sphenopsids, and pteropsids retains its validity. Because of this, proponents of a polyphyletic origin for vascular plants have made much of the Middle Cambrian "Iycopsid" Aldanophyton described by Kryshtofovich. Leclercq has stated in her article, "Evidence of Vascular Plants in the Cambrian" (1956), "It [the discovery of Aldanophyton] positively separates the origin of the lycopsids from the Psilophytales"; and further, "In a wider sense palynology and plant impressions of Cambrian raise the major question of the polyphyletism of the vascular plants."
Because of its important implications in classification as well as its appeal to the spectacular, the evidence for the existence of vascular plants in the Cambrian has become widely adopted as fact in a relatively short time. For ex-ample, in Stirton's new historical geology text, "TIME, LIFE AND MAN" (1959) he notes Aldanophyton as the oldest known land plant in which, ". . . vascular bundles have been traced through the stems." As his authority Stirton refers to Leclercq's 1956 paper. Sporne, in an invitation paper appearing in the May, 1959, issue of the American Journal of Botany, also alludes to Leclercq's description of Kryshtofovich's Aldanophyton. Even more recently, in the June, 1959, issue of Evolution, Axelrod has written a convincing article supporting the polyphyletic origin of vascular plants from algal ancestors. He has placed considerable emphasis on the "Aldonophyton-Drepanophycus line of evolution" described by Leclercq in her 1956 article. Axel-rod states, ". . . that the phylum Lepidophyta [lycopsids] was already established by the Middle Cambrian is shown by the occurrence of Aldanophyton in Siberia (Krystofovich, 1954)2 which is represented by several stems [there are 4] one up to 8.5 cm. long, with spirally arranged microphyllous leaves." For the sake of accuracy, it should be pointed out that in the generic and specific descriptions pre-pared by Kryshtofovich, no defiinte arrangement of the enations or scars on the axes is claimed nor has a vascular bundle been described in the enation. The presence of the latter is a rather important criterion of a lycopsid microphyll. Like the other authors, much of Axelrod's argument for polyphylesis is based on what is considered to be valid evidence for the existence of vascular plants in Cambrian times.
Influenced by Leclercq's 1956 paper, I too have enthusiastically described to students of paleobotany the earliest record of a vascular plant in the Cambrian. My opinion, that Aldanophyton was truly a vascular plant, was influenced almost entirely by a portion of the translated work of Kryshtofovich which Leclercq quotes. This translation into English was obtained from Hoeg of the University of Oslo. I quote from this translation, "The shoot [of Aldanophyton] is densely covered with the delicate appendages (leaves) which are up to 9 mm. long. On the impression the edge of the shoot is uneven, as if dentate due to form of the thickenings and the arrangement of the appendages. In some places it is possible to trace a thin stripe, a vascular bundle right out to the base of the thickenings. . . ." I presumed, as have others, that remains of xylem had been found thus validating the presence of the vascular bundles in Aldanophyton. Later in reading a translation of the Kryshtofovich paper (1953) originating from the Canadian Geological Survey I discovered some points of fundamental disagreement with the translated passage cited by Leclercq. At no point in the entire rendition obtained from the Canadian Government are vascular bundles or vascular tissues described. The sentence describing the presence of vascular bundles in Leclercq's paper was translated by the Canadians as follows: "In places a thin rod-conducting bundle may be traced as far as the base of the enations (leaves)." Further, at the end of the next paragraph, there is the following revealing statement: "During the microscopic examination of the transverse microsection it became evident that the fossilized body of the shoot was depressed, etc. . . . no obvious cellular structure could be determined, although traces of carbonaceous substance were discernible amid the granules of the rock matrix." In other words, the proof that vascular tissue is present and that Aldanophyton is a vascular plant is completely lacking. When so much significance is attributed to 4 specimens of a single organism in deter-mining the classification of vascular plants, I think we are
2 - Date should be 1953. Given as 1954 in the paper by Axelrod.
entitled to the demonstration of vascular tissue. With this in mind it is indeed disturbing to find Aldanophyton de-scribed as an unequivocal vascular plant. It is far from this and the other possibilities need discussion.
Two alternatives are presented based on comparisons with extant and fully described extinct floras. The first and most obvious is that Aldanophyton is some kind of alga. When one considers the diversity of form and high degree of internal and external differentiation among the Laminariales and Fucales, coupled with the fact that the plant fossils were associated with marine organisms, one can hardly dismiss the possibility of some algal affinities for Aldanophyton. For example, Sargasszttn is an alga showing differentiation which could pass, on superficial examination, as that of a vascular plant. The high degree of internal and external differentiation simulating features of primitive vascular plants are summarized for various species of Sargassum by Fritsch (1952) as follows: "The Eusargassums comprise about two-thirds of the known species and are essentially confined to tropical seas. In them the terete or angular branches of the first and higher orders are spirally arranged and bear numerous laterals of limited growth in which the basal "leaf" is usually the most conspicuous. These foliar organs, which are sometimes very narrow, commonly possess a serrate margin and are usually provided with an obvious midrib. In certain species the long axes bear wartlike outgrowths giving them a spiny or verrucose appearance."
Obviously there is no intention to give the impression that Aldanophyton is a member of the Eusargassums. Of importance, however, is the observation that algae have achieved differentiation comparable with that described for the Cambrian fossil. Thus it is equally reasonable to conclude that Aldanophyton is an alga and not a vascular plant.
A second possibility is that Aldanophyton is a nonvascular, green land plant. This is not meant to imply that it had to be a bryophyte as we know them today. However, bryophytes provide us with our only means of comparison. When I mentioned the possibility that Aldanophyton might be similar to a modern moss it was suggested that I make comparisons with the extant Australian species Dawsonia superba, one of the largest of all moss plants. The specimens I have seen attain a length of about 25 cm. Near the apex, of the only slightly flattened gametophyte, the axis is 4 mm. in diameter. The upper portion is covered with lycopsid like leaves, up to 3.5 cm. long and arranged in a beautiful spiral. It is clear that if such a plant, minus its sporophyte, was found as a compression fossil it would be just as logical to include it in the Lycopsida as to include Aldanophton. Yet, according to our present classification, Dawsonia is a nonvascular plant. Further, Dawsonia shows internal differentiation of its main axis into a centrally-located, conducting-rod and each leaf contains a small trace continuous with the central strand. This type of internal differentiation is common among the Musci. I believe this evidence emphasizes the importance of demonstrating vascular tissue before final conclusions are made as to whether a fossil plant is vascular or nonvascular, especially one assuming so much importance in plant classification.
Many different spore types have been described from Cambrian rocks. Because of their diversity and ornamentation it has been suggested that these were produced by vascular plants. There are many possible explanations of their reported presence in these ancient deposits, and even if validated as Cambrian in age, the fact that they have the appearance of vascular plant spores has little meaning. It must be remembered that not all land plants are vascular plants. For example, many bryophytes have thick, highly ornamented spore walls which are identical with those of primitive vascular plants.
One of the more comprehensive descriptions of the ornamentation of spores of extant bryophytes was prepared by Elizabeth Knox (1939). The spores illustrated by Knox, especially those of the Hepaticae, exhibit a degree of variability in ornamentation and size approximating that found in the spores of vascular plants. This high degree of similarity between the two prompted Miss Knox to conclude: "Except where fossil spores are found in organic union with recognizable parent material, however, there can be no certainty as to their relationships." This statement, in my opinion, applies to any valid Cambrian or pre-Cambrian spore flora thus far described.
Based on the foregoing analyses of evidence the following
conservative conclusions can now be made about the com-
position, origin and evolution of early vascular plants.
1). The Middle and Upper Devonian floras are heterogeneous and not composed of just one group—the Psilophytales.
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NATIONAL SCIENCE FOUNDATION
The Division of Biological and Medical Sciences of the National Science Foundation announces that the next closing date for receipt of basic research proposals in the Life Sciences is January 15, 1961. Proposals received prior to that date will be reviewed at the spring meetings of the Foundation's advisory panels and disposition will be made approximately four months following the closing date. Proposals received after the January 15, 1961, closing date will be reviewed following the summer closing date of May 15, 1961.
The next closing date for submission of proposals for specialized biological facilities is March 1, 1961. The NSF has two programs for support of facilities, one for general graduate level university laboratories and the other for specialized biological facilities. The latter are defined as discrete research installations which are unique, one-of-akind, or at least less than ordinary in that they are not a usual part of a university department and may represent either new ventures or the more traditional establishments.
Inquiries should be addressed to the National Science Foundation, Washington 25, D. C.
Finally, I am not aware of any evidence which supports the polyphyletic origin of vascular plants. However, in view of the work of my colleagues on the early vascular plants it can be said that the monophyletic origin of vascular plants from the psilophytes is not as assured as it was 20 years ago. We must, however, continue to recognize the tracheophytes as a natural unit of chlorophyllous plants.
1. Andrews, H. N. 1959. Evolutionary trends in early vascular plants. Cold Springs Harbor Symposia on Quant. Biol. 24:217-234.
2. Andrews, H. N. and Karen S. Alt. 1956. Crocalophyton a new fossil plant from the New Albany Shale and some comments on the origin of land vascular plants. Ann. Mo. Bot. Gard. 43:355-378.
3. Axelrod, D. I. 1959. Evolution of the psilophyte paleo flora. Evol. 13:264-275.
4. Delevoryas, T. 1955. The Medullosae—structure and relationships. Palaeontographica. 97 Ser. B: 114-167.
5. Fritsch, F. E. 1952. The structure and reproduction of the algae. Vol. II. Cambridge Univ. Press. Page 341.
6. Kidston, R. and W. H. Lang. 1917-21. Old Red Sandstone plants showing structure, from the Rhynie chert bed, Aberdeenshire, Parts I-IV. Trans. Roy. Soc. Edinburgh 51-52.
7. Knox, Elizabeth. 1939. Spores of Bryophyta compared with those of
Carboniferous age. Trans. Bot. Soc. Edinburgh. 32: Part 4. 477-487.
8. Kryshtofovich, A. N. 1953. Discovery of lycopodiaceous plants in the
East-Siberian Cambrian. Dokladi Akad. Nauk SSSR. 91:1377-1379.
9. Lang, W. H. and I. C. Cookson. 1935. On a flora, including vascular land plants, associated with A9onograptus, in rocks of Silurian age, from Victoria, Australia. Phil. Trans. Roy. Soc. London 224B: 421-449-
to. Leclercq, S. 1954. Are the Psilophytales a starting or a resulting point? Svcnsk Bot. Tidskr. 48:301-315.
u. . 1956. Evidence of vascular plants in the Cambrian. Evol. 10:109-114.
News Items From the American Society
At the recent meeting of the American Society of Plant Taxonomists at Stillwater, Oklahoma the following officers were re-elected to serve one year terms :
Dr. Mildred Mathias (University of California at Los Angeles) Chairman of the council for 1961.
Dr. C. Ritchie Bell (University of North Carolina) Secretary for 1961.
Dr. Richard W. Pohl (Iowa State University) Treasurer for 1961.
Other appointments made by the Council are as follows: Dr. Rogers McVaugh was reappointed as editor of Brittonia.
Dr. Rolla Tryon (Harvard University) and Miss Annetta Carter (University of California at Berkeley) were appointed to serve four year terms on the editorial board of Brittonic.
Dr. A. E. Radford (University of North Carolina) was appointed as the Society's representative on the editorial board of the American Journal of Botany.
Dr. Robert Thorne (University of Iowa) was appointed as the American Society of Plant Taxonomists' representative to the American Association for the Advancement of Sciences.
Dr. Reed Rollins (Harvard University) was appointed as the Society's representative to the American Institute of Biological Science.
Dr. Robert Ornduff, University of California, Berkeley, received the Cooley Award for the best paper presented at the annual meeting of the Society. His paper was entitled "Hybridization between Lasthenia and Crockeria (Co1npositae) : its taxonomic and evolutionary implications.
NEWS AND NOTES
Recent changes in personnel of the Department of Botany at Yale: Paul B. Sears has retired as of July 1, 1960. Oswald Tippo has left his post as Chairman of the Department to become Provost at the University of Colorado. Theodore Delevoryas has left to become Associate Professor in the Department of Botany at the University of Illinois. Kenton L. Chambers has left to become Associate Professor and Curator of the Herbarium at Oregon State College. Arthur W. Galston became Chairman of the department on July 1, but during the year 196o-61 he will be on leave in Australia, and Norman H. Giles will serve as Acting Chairman. Ian M. Sussex has been appointed Associate Professor on July 1, 196o, and will teach courses in anatomy and developmental morphology. Diter H. von Wettstein of the Forest Genetics Institute in Stockholm has been appointed Associate Professor effective July 1, 1961. He is expected to set up an electron microscopy laboratory. William S. Hillman has been appointed Assistant Professor. John H. Miller has been appointed Instructor. Derald G. Langham, formerly of the Department of Genetics in Caracas and Maracay, Venezuela, has been appointed Lecturer.
HUMANE BIOLOGY PROJECTS
The Animal Welfare Institute, on the advice of scientists and educators who share its belief that animals in school should always be kept in the maximum possible good health and comfort, has prepared a new free illustrated manual for high school teachers entitled "Humane Biology Projects." The manual, which will be available upon request to teachers, includes representative biology projects for teaching and for helping students with their projects for Science Fairs.
"Humane Biology Projects" was prepared with the assistance of botanists, zoologists, physiologists, ecologists and others who agree with the Institute's position that the constantly increasing numbers of cruel experiments being carried out by untrained youths mean not only unnecessary suffering on the part of animals but demoralization of young people at a time in their lives when every effort should be made to develop humane feelings of sympathy, kindness and responsibility.
The following rules concerning science teaching in the public schools have been adopted by the Florida State Department of Public Instruction, and it is hoped other States will soon follow suit:
Another manual which the Institute provides free to teachers, teachers' colleges and libraries is a 46-page illustrated booklet entitled "First Aid and Care of Small Animals." This booklet, which is intended to increase the student's understanding of the need of wild animals and to inculcate a humane attitude toward them, was first published in 1955, and the fourth edition appeared in 1959. To date, approximately 32,000 free copies have been distributed.
Copies of both "Humane Biology Projects" and "First Aid and Care of Small Animals" may be obtained by writing to the Institute, 22 East 17th Street, New York 3, New York. Single copies are available without charge to teachers, librarians and others who work in the educational field; others may purchase at cost: "Humane Biology Projects" $.2o; "First Aid and Care of Small Animals" $.35. Copies in bulk will be provided without charge to those in teachers' colleges who give the manuals to prospective teachers.
Dr. R. Lēvēque is currently in Ecuador as an agent of UNESCO and the "Charles Darwin Foundation," establishing a field research station and carrying out other functions for these organizations on the Galapagos Islands. Since the work at this field station will touch on many phases of biology, a small working library needs to be established. Suggestions for botanical literature and contributions of such for the library will be appreciated. Contributions should be sent to Dr. R. Lēvēque, c/o Naciones Unidas, Casilla 2951, Quito, ECUADOR.
A Department of Botany has been establishd at Ege University (Izmir—Turkey). This new department is in need of aid from botanists and botanical institutions. Help in the form of contributions of collections of books, periodicals and reprints in any field of botany will be appreciated. In addition, the Department is anxious to obtain samples of plants as well as instruments, models and classroom charts that may be available as extras in departments that no longer need them. Contributions should be sent to Prof. Dr. Yusuf Vardar, Department of Botany, University of Ege, Bornova—Izmir—TURKEY.
Establishment of a Card File on Current,
Dr. Raymond C. Jackson, of the Department of Botany, University of Kansas, Lawrence, Kansas, is establishing a card file on all research problems in the field of plant taxonomy that are currently and actively underway in North America. All botanists involved in taxonomic work are earnestly requested to support this project, which is under the sponsorship of the American Society of Plant Taxonomists, by sending to Dr. Jackson information on your cur-rent research and the research of your students. Such in-formation should identify the taxon or taxa under investigation, the primary trend or emphasis of the project (morphological, ecological, cytological, etc.) and the name and address of the person or persons actually doing the research. If the project is being supported by N.S.F. or other funds this information might be included, as might any tentative schedule for completion of the project.
The object of the file is to eliminate duplication of taxonomic effort and to foster cooperation between those who might be working on a common problem from different approaches. Please address your information, and inquiries, to Dr. Jackson.
Since June 15, 196o, the Museum Building of The New York Botanical Garden, which houses the museum, the library, the herbaria and the paleobotanical collections, has been temporarily closed to visitors. Extensive renovations and rehabilitations of the monumental building, opened in 1900, will include new heating, new plumbing, new wiring, new lighting, and the installation of a new elevator. This much-needed work was undertaken on behalf of the Garden by the Department of Parks of the City of New York, and is expected to be completed by or before the end of the year. The administrative and scientific staff have found temporary quarters in other buildings of the Garden, and a skeleton library of reference works and cur-rent publications is available. It is estimated that the Museum Building will re-open about January 1, 1961.
The Passing of Two Pioneers
BY KENNETH V. THIMANN
The deaths during the past year of both Fritz Kōgl and Peter Boysen Jensen may be said to mark the end of an era in that active field which encompasses plant growth and growth substances. Both men made substantial contributions to knowledge, and both more or less withdrew later on from the field, though for different reasons.
Boysen Jensen was 27 when he performed his well-known experiment on the conduction of phototropism across a cut surface (1910). Coleoptile tips were illuminated from one side, cut off and replaced; after a short period in darkness they were seen to curve towards the side which had been lighted, and the curvature took place not only in the tip but also in the part below the cut surface, showing that the "stimulus," or as we should now say the asymmetric distribution of auxin, had been transmitted across the cut. Boysen Jensen's interpretation of the experiment at the time was somewhat complicated, but in hindsight we see that this was the primary demonstration that growth is controlled by a diffusible substance. In the thirties Boysen Jensen came back to the growth field, proving that asymmetric auxin distribution under the influence of gravity also took place in root tips, which form auxin when supplied with osmotic material, and in shoots of whole plants. He wrote the first book on the subject, "Die Wuchsstoffe," which was translated into English by Avery and Burkholder as "Growth Hormones in Plants" (McGraw Hill, 1936). After a few more years, however, the administrative work of the Professorship took much of his time, and only after retirement could he return to his first love, experiments on growth. He was doing an experiment on the day before he died.
As a young man Boysen Jensen had studied in Copenhagen with Warming, the ecologist, and had spent shorter times in Germany with Pfeffer and in Switzerland with Schulze,—both physiologists. It was Warming who urged him to go into physiology. (How many of us would direct our best students into another field than our own?) All these studies gave him a very broad botanical viewpoint; next to his growth and auxin studies he had a strong interest in photosynthesis at the field level, and he published also on galls, on differentiation and even on plant geography. His plant physiology text had two Danish editions and was translated into German (Jena, 1939). This breadth was, alas, more typical of the last generation than of the present, for the demands of specialization have forced most of us to substitute depth for breadth.
Kōgl was a very different type, who made his botanical contributions through chemistry. Born and trained in Germany, he went to Utrecht as Professor of Organic Chemistry in 1930 and soon came under the influence of F. A. F. C. Went, the Professor of Botany, in whose lab-oratory the work of his son F. W. Went, and of Dolk, Heyn, van Overbeek, van der Weij and du Buy was unraveling the distribution and function of the growth sub- stance that Boysen Jensen had earlier shown to exist. This development was made possible by F. W. Went's demonstration that the growth substance could be quantitatively diffused into agar blocks. Furthermore, Boysen Jensen's junior, Niels Nielsen, had shown that Rhizopus secretes a plant growth substance into its culture medium, so that the way was open for chemical extraction. With Haagen Smit and Miss Erxleben, Kōgl began a series of researches on these growth substances, soon called "auxins." They examined numerous microorganisms but finally settled on human urine as a source material. But their initial isolations of "auxins a and b" and of some derivatives proved unconfirmable subsequently, and the work of these early years is still lacking a satisfactory explanation. How-ever, the isolation of indole-3-acetic acid as a major auxin from urine in 1934 brought the subject on to firmer ground, especially as the same substance was independently isolated in America from Nielsen's culture of Rhizopus, and shown to be the auxin produced by this fungus. The role of indoleacetic acid as the major naturally-occurring auxin in both higher and lower plants is now established. The synthetic compounds that dominate the applied auxin field (2,4-D etc.) took off from the structure of indoleacetic acid. But like his predecessor Ruzicka, who had had a strong bent towards the biochemistry of plants, Kōgl had interests in many aspects of biochemistry, including fungus pigments, tumor metabolism and especially other growth substances. In 1935 he and Tōnnis isolated a yeast growth-promoting substance, termed Biotin, which has since taken its place as a major member of the Vitamin B group.
Kōgl's interests were far from being restricted to the chemical aspects of this work; he directed such studies as the variation in auxin bioassay with time of day, the role of auxin in tropisms, and the effect of diet on auxin levels in human urine. But, like Boysen Jensen, he left the field during the war years, and though he spoke several times of returning to a reinvestigation of "auxins a and b," he be-came interested in other topics. Nevertheless, he continued to puzzle over the auxin problem to the end of his life, and several of his collaborators returned to researches on these auxins, but without success.
As a born German who had become a naturalized Dutch citizen, Kōgl might have been put in a difficult position by war. But he stood firmly by his adopted country and his personal popularity was undiminished.
Whether Kōgl and Boysen Jensen ever saw much of one another is not recorded. They were both at the Botanical Congress in Amsterdam in 1935, and Kogl lectured widely in Europe on the work of his laboratory. Boysen Jensen, perhaps because of indifferent health, was no great traveler or public lecturer. Indeed he had few collaborators and seems to have preferred to work alone, while Kōgl did virtually all his work through students or assistants. But by now it is a platitude to say that successful scientists include all types of personality; about the only thing they have in common is a devouring interest in their work. Certainly this characteristic was exemplified in these two men, and botany owes them a great debt.
1960 Annual Meeting (Plant Science Seminar) of the
The University of Colorado College of Pharmacy was host to the First Annual Meeting (Plant Science Seminar) of the American Society of Pharmacognosy from June 30 to July 2, 196o. The program committee included the following:
Dr. Maurice C. Andries, Chairman Dr. Melvin R. Gibson Dr. Frank L. Mercer
The members were welcomed by Dean Curtis H. Waldron
of the School of Pharmacy at the University of Colorado.
a. The Seminar activities included a field trip to the Rocky Mountain National Park. Dr. John W. Marr of the Institute of Arctic and Alpine Research of the University of Colorado gave an interesting lecture on the biological projects they are undertaking in these areas. Papers dealing with research and teaching in pharmacognosy were presented, including-
Dr. N. R. Farnsworth, Pittsburgh University.
by Gibberellic Acid on Mentha piperita," by Dr. G.
Gerstad of Wayne State University.
The present officers of the Society are:
Varro E. Tyler, Jr., President
Norman R. Farnsworth, Vice-President Rolf S. Westby, Secretary
Frank A. Crane, Treasurer
Edward P. Claus, Executive Committee Carl H. Johnson, Executive Committee David P. Carew, Executive Committee
This Society has been formed by the pharmacognosists of the United States to formalize and perpetuate the standards and ideals of the Plant Science Seminar and has for its purpose ". . . . to promote the growth and development of pharmacognosy, to provide the opportunity for association among the workers in that science and in related sciences, to provide opportunities for presentations of research achievements and to promote the publication of meritorious research." Membership is also open to graduate students and workers of other nations.
American Institute of Biological Sciences Translation Program
The American Institute of Biological Sciences is currently translating and publishing seven Russian research journals in biology. These journals are translated with support from the National Science Foundation, which is eager that such information be more widely distributed to biologists throughout the world. It is hoped that this material will aid biologists in research, prevent duplication of work, give some idea of the work being done by Soviet scientists in the field of biology, and also bring about a bet-ter international understanding among scientists.
Because of the support of the National Science Foundation, the AIBS can offer these translations at a fraction of their publication cost, with even further price reduction to AIBS members and to academic and non-profit libraries. This reduction, the AIBS feels, places the translation within the reach of all biologists.
The journals currently being translated are: Doklady: Biological Sciences Section; Doklady: Botanical Sciences Section; Doklady: Biochemistry Section; Plant Physiology; Microbiology; Soviet Soil Science; and Entomological Re-view.
In addition to its program of Russian Biological Journal translations, the AIBS has instituted a separate program of translation and publication of selected Russian Monographs in biology.
It was felt that the program of Journal translations was not sufficient to cover all of the significant work being done in all fields of biology by Russian scientists. With the aid of competent authorities, the AIBS has translated and published six Russian monographs and one monograph is in the process of being published. In addition, several prominent monographs in various biological areas are being considered by the AIBS and the National Science Foundation for translation and publication. The monographs that have been published are: Origins of Angiospermous Plants by A. L. Takhtajan; Problems in the Classification of Antagonists of Actinomycetes by G. F. Gauze; Marine Biology, Trudi Institute of Oceanology, Vol. XX, edited by B. N. Nikitin; Arachnoidea by A. A. Zakhvatkin; and Arachnida by B. I. Pomerantzev. The manuscript for Plants and X rays by L. P. Breslavets is in the final stages of preparation and should be published early in 1961.
Additional information pertaining to this program may be obtained by writing to the American Institute of Biological Sciences, 2000 P Street, N. W., Washington 6, D. C., U. S. A.