Seeds of the Cruciferae of Northeastern North America

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Abstract
A seed key including 118 spp. has been prepared in 2 parts: seeds from (a) dehiscent fruits and from (b) indehiscent fruits. The key includes only those characters necessary for a rapid identification of "unknowns," such as size, shape, color, and seed coat. Special attention has been paid to seed coat surface. Magnifications as low as 45x have revealed considerable structural differences among the spp. in question. At the end of the key, a full taxonomic descr. of the spp. is given including statistical data, distr., source of seeds studied and specific seed drawn. In addition to supplementing the key, this detailed descr. research may contribute to a more satisfactory natural classification of the family, in that it involves further detailed factual information on the seed, more especially the seed coat, wing and hilar area. A seed glossary of over 125 terms has been prepared with a view to its use not only in the Crucif erae, but for seeds in general. To insure standardization of terms, Latin equivalents and source of definitions are given. To test the validity of characters, selected spp. have been chosen and seeds from many samples (30-60) studied (totalling over 800 seeds per sp.). Records of the exact source of seed have been kept: (a) locality, (b) colony, (c) specific plant in colony, (d) part of plant, base or apex, (e) part of fruit, (f) part of the growing season. Mass collections were made in the Chicago area in the summer of 1948. In addition seeds of these spp. were obtained from other regions of N. America. Highly variable spp. as to shape, size or color are: Sisymbrium officinale, Erysimum cheiranthoides, Alliaria officinale, Diplotaxis muralis. etc. The variability in shape and length in Sisymbrium officinale is related to position of seed in fruit. Differentiation of seed coat in Diplotaxis muralis appears to be environmentally controlled. Other spp. display highly constant characters. The 12 pls. of drawings include illustrations of 92 spp. and 68 terms of the glossary. Tables accompany the mass collection studies. The bibliography is annotated.

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