COMPOSITION OF VOLATILES IN RELATION TO TAXONOMY OF AMERICAN ALLIUMS

Abstract

The North American species of Allium exclusive of A. schoenoprasum and A. tricoccum of Old World affinity are grouped on the basis of morphological similarity into eight discontinuous species alliances typified by A. acuminatum, A. campanulatum, A. canadense, A. cernuum, A. falcifolium, A. kunthii, A. sanbornii , and A. validum , respectively. Representatives of each of these alliances were compared with respect to volatile constituents responsible for characteristic odors by means of gas chromatography. Results indicate that these volatiles provide evidence of relationship useful in the classification of alliums. Uniformity was found in composition of volatiles in the representatives of the A. canadense, A. cernuum, A. kunthii , and A. sanbornii alliances. Variation was observed in the A. acuminatum, A. campanulatum , and A. falcifolium alliances. A. validum was the only species of its alliance studied. Vapors of A. validum contain mostly n ‐propyl sulfides (onion‐like odor) as does the cultivated A. cepa . Methyl sulfides (cabbage‐like odor) predominate in the A. sanbornii alliance. A few species of the A. acuminatum and A. falcifolium alliances contain mainly allyl sulfides (garlic‐like odor).