Reed C. Rollins

The Cruciferae of continental North America : systematics of the mustard family from the Arctic to Panama

This monumental work culminates over fifty years of research and study by the worlds leading authority on the important plant family Cruciferae. Worldwide, the mustards, which are morphologically diverse and economically valuable, comprise roughly 350 genera and perhaps 3,500 species. Included in the Cruciferae are vegetables (radish, cabbage, broccoli, turnip, caulifower, Brussels sprouts), ornamental species (stock, sweet alyssum), familiar condiment sources, the bases for both edible and industrial oils, and of course the annual wildflowers and weeds that blanket so many landscapes in spring and summer. Taxonomic criteria and the systematics of every species of the family known to occur in continental North America, including the weeds and cultivated introductions from Europe and Asia. Such coverage, much of it drawn from the authors own research, has not been attempted since 1838. The book describes 8 new species and 16 new varieties and reassigns 32 taxa to different genera or species. In all, the book treats 248 subspecies, varieties, and hybrids, (243 of them native to North America and mostly endemic), 778 species (677 native and mostly endemic), and 99 genera (39 wholly endemic). Identifcation keys, description, and area of occurrence are given for all taxa. The 113 plates illustrate 346 species and varieties (some more than once), and include 341 line drawings, 60 photographs, 20 photomicrographs, and 77 scanning electron micrographs (the micrographs are mostly of pollen grains, seeds, chromosomes, and surface hairs). Introductory chapters offer general information on the Cruciferae, principal features of family members, taxonomic criteria, and methods of treatment. The work concludes with an appendix of new names, a list of literature cited, and an index.<

The Role of the University Herbarium in Research and Teaching

under the direct influence of the factors that mold it into its actual form. But the image has as its shaping influences only the secondary conceptions derived by persons. These conceptions come in a wide variety of ways, often unrelated or remote from the actuality of the current nature of the institution itself. Such conceptions are usually based on what the institution was like, not on what it is like. The lag phase between a current institution and its previous state which is the source of its image may be a long period or a short one, depending upon the nature and speed of communication but the important item to point up is that the basis of an image follows the subject and is rarely if ever current with it. We see the situation I have described in many facets of education. The weak department of a University, formerly strong, still drawing in many graduate students on the basis of an established image. Or the converse, a strong present-day department, from the point of view of its faculty and facilities, struggling against the image of former weaknesses. Such examples could be many times multiplied and much extended but my present purpose is to examine the situation of herbaria in the University in the frame of reference I have just described. I am considering the matter primarily from the viewpoint of herbaria in the United States. The relation of herbaria to botanical science has completed a full cycle. In the early phases of botanical activity in the United States and lasting nearly to the turn of the last century, herbaria were respected centers of teaching and research. The most eminent men of botany were associated with them. The vitality present was evident on all sides and the significant biological questions of the day were as importantly dealt with by these men, Asa Gray, for example, as by any other biologist. The questions being asked were broad in scope and in their impingement on science and philosophy as a whole. This was a period when the institution we call an herbarium was central to botany and the image that followed was a favorable one. Having established its place in the University and in the Museum, the herbarium attracted less venturesome scholars, who narrowed the dimension of their activities. So absorbed were they with the intricacies of their subject that their communications reached an ever narrowing audience. With a few exceptional situations, it was almost as if the principal business of the herbarium was no longer concerned with botany at large or biology at large but placed greatest emphasis on the herbarium as an end in itself. Into this period of some decades, the good image lingered and those associated with herbaria cast long if not entirely wholesome shadows. However, developments in other areas of botany were now taking place and a vigorous challenge to herbariumconnected botanists from other branches of the subject brought the herbarium and its image into closer focus. Indeed, the image became one that reflected stultification, diffidence and rigidity without sinews to bind it to the main stream of biological teaching and research. It is this image that we still have with us, to some extent, even though we are now moving toward the zenith of a new cycle. The herbarium image is definitely in the lag phase but the herbarium is now back in the lag phase. Our institution, the herbarium, has been on the advance for some little time now but our image is holding us back. A new image more closely in focus with the present reality of the University herbarium is badly needed. I would be greatly heartened if I knew the forces that will ultimately replace the poor image with a good one were as virulent

TAXONOMIC INTERPRETATIONS OF DISCONTINUITIES IN FLOWER SIZE

Summary Large differences in the sizes of floral parts producing discontinuities between different individuals or between different populations of the same or closely related taxa require different taxonomic interpretations. Autopolyploidy may produce such discontinuities as in Thelypodiopsis linearifolia (Gray) Al-Shehbaz of southern Arizona, but the single individual with large flowers cannot be considered to be another taxon. A different situation was found in populations differing from Pennellia longifolia by a large jump in the size of floral parts. In this case, there were populations of plants which were not polyploid with respect to P. longifolia and the large size differences were consistent throughout the populations. These populations are recognized as a new species which is named in honor of Dr. Rogers McVaugh who first collected it in the Sierra Madre Occidental of Durango, Mexico. Quantitative variation within a given taxon at the species level or below is usually of a continuous type. In fact, one of the frequent tests as to whether a taxon is solidly characterized and properly interpreted is how it measures up as to continuous quantitative variation as opposed to sharply discontinuous differences. Such a test is possible when abundant material is available and measurement data can be assembled. However, the taxonomist is quite often faced with the necessity of handling situations where large differences in size of parts and organs occur in different gatherings of plants, but the specimens available for study are few in number. Here, a sensible test for continuity cannot be applied. Then how are the disparate plants to be treated taxonomically. Two cases where large quantitative differences in flower size occur will be dealt with where the taxonomic interpretation is very different. The taxa involved are members of the Cruciferae.