Evolution and Diversification in the Sapindales
Pirani, José R. , Menezes, Nanuza L. .
Floral anatomy of Galipea, and its bearing on the evolution of tubular flowers in Neotropical Rutaceae.
Most genera of the neotropical subtribe Galipeinae (tribe Galipeae, Rutoideae) have tubular, somewhat showy, flowers. Several forms and degrees of fusion between the flower organs have been described in the group, including the union of petals into an apparently sympetalous corolla, the joining of the stamens inter se and to the corolla, and the partial to complete connation of carpels. The fact that Galipea and some other genera in the subtribe bear only two fertile anthers plus five or more staminodes is also intriguing, since generally the Galipeae exhibit isostemony. To elucidate the anatomic condition of these traits, and to establish an accurate coding scheme for characters state in phylogenetic studies, a morpho-anatomic study of the flower of four species of Galipea was carried out. Using cross-sections of pickled material, the patterns of vascularization, position, and union of the flower segments were investigated. The following results are noteworthy: (1) the filaments are truly connate forming a staminal tube, although (2) the tubular corolla is not genuinely sympetalous, but postgenitally fused to the five filaments which alternate with the petals; (3) the petals are distally coherent to each other and adherent to the filaments by means of capillinection (close intertwining of dense trichomes); (4) the three abaxial staminodes are homologous to fully sterilized stamens, while the two others arise from the distal part of the two fertile stamens. The implications of these data for understanding the evolution of tubular flowers in Galipea and related groups are discussed. Particularly interesting is that pseudosympetaly in Galipea arises by a different mechanism than that reported for the Australian genus Correa (tribe Boronieae, Rutoideae).
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1 - Universidade de São Paulo, Departamento de Botanica, Caixa postal 11461, Rua do Matão, 277, São Paulo, São Paulo, 05422-970, Brazil
Presentation Type: Symposium or Colloquium Presentation
Location: Boulevard B/Hilton
Date: Tuesday, July 10th, 2007
Time: 12:00 PM