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Systematics of south american tripsacum gramineae


American Journal of Botany 68(2): 269-276
Systematics of south american tripsacum gramineae
Tripsacum is widely distributed between 42.degree.N and 24.degree.S. In South America the genus extends around the Amazon and Orinoco basin, and from the Caribbean coast south to Brazil and Paraguay. The most common South American taxon is T. dactyloides (L.) L. var. meridonale de Wet and Timothy (2n = 36), which differs from North American representatives of the species in having subdigitate racemes usually appressed with the apical male sections typically curved. Closely related to T. dactyloides, but occupying more seasonally moist and dry habitats, is T. australe Cutler and Anderson. This species is robust with the basal leaf sheaths tomentose and the much elongated culms becoming decumbent in older plants. Smaller plants, with essentially erect culms and leaf sheaths on the culms hirsute rather than tomentose, are recognized as T. australe var. hirsutum de Wet and Timothy. The 2 varieties of T. australe are both diploid (2n = 36) and cross to produce fertile hybrids. They also cross with T. dactyloides var. meridonale (2n = 36), but these hybrids are partially sterile. T. cundinamarce de Wet and Timothy (2n = 36) is a robust species with glaucus leaves. It resembles robust specimens of T. dactyloides in having glabrous leaf sheaths, but can always be recognized by inflorescences that are composed of racemes arranged along a several-noded primary axis. This species is confined to moist habitats, while T. dactyloides occupies a range of habitats in South America. T. peruvianum de Wet and Timothy is a gametophytic apomict with 2n = 72, 90 or 108 chromosomes. It is characterized by an erect growth habit and strongly hirsute leaf sheaths. The cultivated Guatemala grass, T. andersonii Gray, occurs spontaneously in the mountains of Venezuela, Colombia and Peru. This sexually sterile species is characterized by 2n = 64, and may combine 54 Tripsacum and 10 Zea chromosomes in its genome. Electrophoretic patterns of seed storage proteins confirm the validity of recognizing T. cundinamarce as distinct from T. dactyloides and T. peruvianum as distinct from T. australe.


Accession: 006574657

DOI: 10.2307/2442859



Related references

Systematics and biogeography of South American Tripsacum. Dissertation Abstracts International, B 42(9): 3553, 1982

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