Notes on the sexual condition of Myriophyllum aquaticum (Haloragaceae).

TORRES ROBLES, SILVIA SUSANA; PETER, GUADALUPE; TUR, N.M.

PHYTON - INTERNATIONAL JOURNAL OF EXPERIMENTAL BOTANY BA ARGENTINA

FUNDACION ROMULO RAGGIO

Año: 2011 vol. 80 p. 133 - 188

0031-9457

Myriophyllum aquaticum (Vell.) Verdc. is native of South America and pantropical in distribution. This species has been cited as dioecious, monoecious and polygamous. The purpose of this paper is to contribute to the discussion of its sexual condition, based on herbarium material and supported by field observations. Herbarium material from Argentina was examined. Also, twenty branches from the Punta Lara Nature Reserve (Buenos Aires, Argentina) were periodically sampled to record the sex of flowers present on each whorl during the flowering period of 2002. Both in herbarium material and in field, we observed specimens with branches bearing female flowers, specimens with branches bearing male flowers, and specimens with female and male flowers on the same branch. Some of these materials also have fruits. Our observations support the idea that M. aquaticum is not a strictly dioecious species, at least in Argentina.