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On the Separation of Two Species within the Ludwigia uruguayensis Complex (Onagraceae)

Elsa M. Zardini, Hongya Gu and Peter H. Raven
Systematic Botany
Vol. 16, No. 2 (Apr. - Jun., 1991), pp. 242-244
DOI: 10.2307/2419276
Stable URL: http://www.jstor.org/stable/2419276
Page Count: 3
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On the Separation of Two Species within the Ludwigia uruguayensis Complex (Onagraceae)
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Abstract

In earlier chromosomal studies, hexaploid (n = 24) and decaploid (n = 40) strains were reported within the species that has been called Ludwigia uruguayensis. Field observations and morphological studies of extensive living collections for which chromosome numbers are available have confirmed that these entities are best treated as two discrete species. The hexaploid species, L. grandiflora, comb. nov., has villous pubescence, sublance???? leaves with a glandular mucronate apex, smaller flowers, and smaller pollen grains. The decaploid species, L. hexapetala, comb. nov., is usually glabrous, with oblanceolate leaves, larger flowers, and larger pollen grains. Octoploid (2n = 64) hybrids between them have been found in southern Brazil and are to be expected wherever they occur together.

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