Resumo

SPERONI, Gabriela; IZAGUIRRE, Primavera  e  BERNARDELLO, Gabriel. On the causes of the differential seed production in the anficarpic species Trifolium polymorphum (Leguminosae). Bol. Soc. Argent. Bot. [online]. 2010, vol.45, n.1-2, pp.57-72. ISSN 1851-2372.

Trifolium polymorphum is recognized as one of the best adapted legume in field conditions. It combines different reproductive strategies such as stoloniferous vegetative reproduction and seed reproduction by two types of fruits produced in underground and aerial flowers. These last ones are chasmogamous and underground flowers are cleistogamous. A higher seed production has empirically been detected in underground flowers rather than in aerial ones. In the present work, embryological studies in aerial and underground flowers were carried out in order to determine the existence of ontogenetic causes which may promote productivity differences in both types of seeds. No embryological pre-zygotic cause explaining aerial flowers low productivity was detected. Aerial and underground seeds share ontogenetic characteristics as both types of flowers showed normal ovule and embryo sac development. Similar nutritional pathways for embryo sacs, embryos and endosperms were also observed. In general, flowering represents a high energetic inversion for plant species. Aerial flowering in T. polymorphum, though subjected to a strong herbivorous pressure, incorporates genetic variability to populations through cross-pollination and succeeds in facilitating long distance dispersion.

Palavras-chave : Trifolium polymorphum; Leguminosae; Seeds; Embryology.

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