Taxonomy of North American species of Allium

Taxonomy of North American species of Allium

Hanelt, P. Book author
Hammer, K. Book author
Knupffer, H. Book author

Gatersleben Institute of Plant Genetics and Crop Plant Research Germany

1992

p.195-204

SB339.A4H3

The genus Allium is represented by 84 species in North America, north of Mexico, or approximately 1/6 of the world's species. Only one species, A. schoenoprasum is represented in the native floras of both the Old and New World. All but three North American species have a base chromosome number of x=7 in contrast to the vast majority of Old World species which are x=8. Allium has been extant in the New World since at least the Tertiary. We recognize two major centers of radiation, one in northern California and Oregon and a second in Texas. Ownbey divided the North American species into nine "alliances", grouping species together often on one or two characters to break these species up into workable sized groups. Attempts by others, notably Traub, to define these as subsections have largely failed due to the number of overlapping characters. Many New World species are poorly represented in herbaria. This has lead to misinterpretation of vaiation in many taxa and general confusion about species limits, particularly in the western US. In recent years, extensive collecting has added to the available material and allowed a reappraisal of characters used in the classification of many of these taxa. In addition to the usual morphological characters, cellular patterns on the bulb coats have long been recognized as valuable in classifying species. SEM studies have added to this value and allowed recognition that the cell pattern of the epidermal layer forming this coat may be important even when the pattern is not evident of the coat itself. Cell patterns and ornamentation on seed coats have also proven valuable. Information from these sources has led to a better understanding of the relationships in the North American group. The outstanding question remaining in the taxonomy and evolution of the North American species seems to be their relationships to the Old World species. The concentration of investigators in both hemispheres on their own native species and the lack of species occurring in both have hampered research on this interesting biogeographical question. [AS]

The genus Allium - taxonomic problems and genetic resources; Proceedings of

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