Aspectos da biologia da reprodução em plantas ornamentais cultivadas no Estado de São Paulo: I - Dichorisandra Thyrsiflora Mikan (Commelinaceae)

Abstract

RESUMO -Foram estudados os possfveis sistemas de reprodu~iio em Dichorisandra thyrsiflora. A esp6cie parece ser predominantemente de fecunda~o cruzada. embora sem urn sistema de autoincompatibilidade definido. Conseqiientemente a autofecund~iio ocoere numa freqiimcia bern menor. Quanto a agamospermia. nenhum fruto foi observado em flores niio polinizadas.Os agentes polinizadores. invariavelmente. sao insetos do genero Bombus. Observou-se que o numero cromossomico da especie e 2n = 38. A analise da microsporogenese mostrou que a meiose e normal com exc~iio de algumas ct!lulas maes de p6len nas quais foi observada a for~iio de pontes cromatinicas em anafases I e II. sugerindo exist&tcia na popula~iio de heterozigotos para inversao . A form~iio de tetrades normais foi de 95% e a viabilidade dos griios de p6len foi alta. 87.2%. Palavras-<:haves: Plantas Ornamentais-Biologia da Reprodu~iio. Dichorisandra thyrsiflora-Commelinaceae. Microsporogenese.ABSTRACI' -(Aspects of breeding system of Dichorisancha thyrsijlora Mikan.) The breeding system of Dichorisandra thyrsiflora was studied. It was found that this is a mainly cross-pollinated species (92%). without a well defined self-incompatibility mechanism. Self-pollination was obtained in 27% of the analysed flowers. and apomixis was not observed. Pollination agents were mainly of the Bombus genus. The chromosome number of the species was 2n = 38. Microsporogenesis analysis showed normal meiosis. with only a few exceptions. in which chromatic bridges formation was observed in the anaphase I and n. suggesting heterozygosity for the inversion. Normal tetrad formation was 95% and pollen viability was high (87.2%).

Recircumscription and taxonomic revision of Siderasis, with comments on the systematics of subtribe Dichorisandrinae (Commelinaceae)

“…1M–O). Only three species of Dichorisandra have had their reproductive biology investigated, presenting typical buzz-pollination, performed by bumblebees (Apidae) and/or sweatbees (Halictidae) ( D. thyrsiflora , Boaventura and Matthes 1987; D. hexandra and D. incurva , Sigrist and Sazima 2015). Information regarding flower visitation in Cochliostema , Geogenanthus , and Plowmanianthus is completely lacking from the available literature.…”

Development of the gametophytes, flower, and floral vasculature in Dichorisandra thyrsiflora (Commelinaceae)

“…16), and pollen is apparently released by the vibration induced by pollen-collecting bees as in many other buzz-pollinated flowers. Vibration-mediated removal of pollen by bees of the genus Bombus has been observed for cultivated plants of D. thyrsiflora (Boaventura and Matthes, 1987;C.R. Hardy, personal observation).…”

“…The stamens are inconspicuously united at the base of their filaments, which are basally adnate to the corolla (Fig. Vibration-mediated removal of pollen by bees of the genus Bombus has been observed for cultivated plants of D. thyrsiflora (Boaventura and Matthes, 1987;C.R. As a consequence of the adnation of these basally fused filaments to the corolla, the otherwise free petals are indirectly united as in Dichorisandra hexandra and certain other Commelinaceae (Rohweder, 1969).…”