Biologia reprodutiva e polinização de duas espécies de Polystachya Hook. no Sudeste do Brasil: evidência de pseudocleistogamia em Polystachyeae (Orchidaceae)

Abstract

-(Reproductive biology and pollination of two species of Polystachya Hook. in southeastern Brazil: evidence of pseudocleistogamy in Polystachyeae (Orchidaceae)). Phenology, floral biology, pollinators, breeding system and natural fruit set of Polystachya estrellensis Rchb. f. and P. concreta (Jacq.) Garay & H. R. Sweet were studied in mesophytic forests at Serra do Japi, and in mangroves at a seashore plain at Picinguaba, respectively. Both study areas are natural reserves in southeastern Brazil. Both species flower in summer, are epiphytes and produce terminal inflorescences with up to 150 non-resupinate flowers. The flowers produce a citric fragrance, mainly in the warmest hours of the day. Both species are pollinated by solitary and social small native bees, which collect pseudopollen from the lip of the flowers. The pollinarium is placed frontally on the head of the bees, when they are collecting pseudopollen. Polystachya estrellensis and P. concreta are self-compatible. The majority of flowers of P. estrellensis (96,7%) is cleistogamous, while P. concreta produces only chasmogamous flowers. The cleistogamous flowers of P. estrellensis present dimensions and number of floral elements identical to the chasmogamous, a phenomenon called pseudocleistogamy. The chasmogamous flowers of P. estrellensis, as well as all flowers of P. concreta are pollinator dependent. The natural fruit set of P. estrellensis was higher than that of P. concreta as a consequence of pseudocleistogamy. In mesophytic forests of the Serra do Japi, in which the fruit set of several orchid species is low, mainly because of pollinator scarcity, the strategy presented by P. estrellensis is an important factor that increases the reproductive success of this species, compared with to the non-autogamous members of Epidendroideae that occur in the same region.Key words -cleistogamy, Orchidaceae, Polystachya, pseudopollen, reproductive biology RESUMO -(Biologia reprodutiva e polinização de duas espécies de Polystachya Hook. no Sudeste do Brasil: evidência de pseudocleistogamia em Polystachyeae (Orchidaceae)). A fenologia, a biologia floral e reprodutiva, e o sucesso reprodutivo de Polystachya estrellensis Rchb. f. e P. concreta (Jacq.) Garay & H.R. Sweet foram estudados em matas mesofíticas semidecíduas da Serra do Japi (Jundiaí, SP), e na planície litorânea de Picinguaba (Ubatuba, SP), respectivamente. Ambas as espécies florescem no verão. Elas são principalmente epífitas e produzem inflorescências terminais com até 150 flores não ressupinadas. As flores exalam odor cítrico suave, principalmente nas horas mais quentes do dia. Ambas as espécies foram polinizadas por pequenas abelhas nativas, solitárias e sociais, que coletam pseudopólen do labelo das flores. O polinário é depositado na face frontal da cabeça das abelhas, enquanto elas recolhem pseudopólen. Tanto P. estrellensis como P. concreta são autocompatíveis. A maioria das flores de P. estrellensis (96,7%) é cleistógama, enquanto P. concreta produz apenas flores casmógamas. As flores...

Pollen and nectar as a reward in the basal epidendroid Psilochilus modestus (Orchidaceae: Triphoreae): A study of floral morphology, reproductive biology and pollination strategy

“…The natural fruit set of P. modestus was low when compared with that of each inflorescence in artificial self-and crosspollinations (Table 2). In experimental conditions, an increase of fruit set occurs when compared with the natural condition of several orchid species and seems to be the most common condition among orchids pollinated by biotic vectors (e.g., Ackerman and Montalvo, 1990;Ackerman and Oliver, 1985;Montalvo and Ackerman, 1987;Zimmerman and Aide, 1989), which include epidendroid orchids occurring in the study area (e.g., Mickeliunas et al, 2006;Pansarin, 2000Pansarin, , 2003bPansarin and Amaral, 2006). The fruit set of nonautogamous orchids, as is the case of P. modestus, is low as a consequence of a deficient pollen transference between plants where scarcity of efficient pollinators seems to be a limiting factor (e.g., Ackerman and Montalvo, 1990;Bierzychudek, 1981;Burd, 1994;Calvo, 1990;Janzen et al, 1980;Schemske, 1980;and references therein).…”

“…and some species of Halictidae bees (Serra do Japi; table 1) took nectar from flowers of P. modestus. Halictidae bees are important pollinators of other orchid flowers in many regions (Catling, 1983;Goss, 1977;Mehrhoff, 1983;van der Pijl and Dodson, 1966;Pansarin, 2000;Pansarin and Amaral, 2006;Singer and Cocucci, 1999), including T. trianthophora in North America, which is pollinated by Augochlora pura (Medley, 1979) and Halictus quadrimaculatus (Lownes, 1920). Although Rothacker (2006) reported capsules with a high level of seed formation in plants of T. trianthophora, no pollinators were observed in Florida.…”

Is the pollination efficiency of long-lived orchid flowers affected by age?

“…Most studies using hand-pollination, however, provide no information on the age of the flowers in the tests (Stort & Galdino, 1984;Calvo, 1990;Galetto et al, 1997;Singer & Sazima, 1999;Singer, 2001Singer, , 2002Singer & Sazima, 2001;Borba & Braga, 2003;Gale, 2007;Peter & Johnson, 2009;Micheneau et al, 2010;Srimuang et al, 2010). In studies mentioning the flower age, hand-pollinations were performed on the first (Borba et al, 1999;Pansarin & Amaral, 2006;Li et al, 2008;Pansarin & Amaral, 2008;Aguiar et al 2011) or second day of floral anthesis (Vieira et al, 2007). So far, there are no reports on the possible differences between fruit set related to the pollinated flower age.…”

A família Orchidaceae no município de Morro do Chapéu, Bahia, Brasil

“…Das 53 espécies encontradas neste trabalho, 43 foram listadas para a Chapada Diamantina por Toscano de (Pansarin & Amaral 2006). Capanemia therezae Barb.Rodr., uma espécie do Sul e Sudeste brasileiros, citada, até então, no nordeste, apenas para Pernambuco (Harley & Mayo 1980;Barros et al 2010;Buzatto et al 2010) (Barros 1987), nove espécies, seguida por Grão Mogol (Barros & Pinheiro 2004), sete espécies, e apenas duas espécies com o Parque Estadual de Itacolomi (Peron 1989).…”

“…Garay & H.R.Sweet (Toscano de Brito 1998;, com a qual é comumente confundida pela semelhança na morfologia vegetativa e floral. No entanto, P. concreta apresenta sépalas mais angulosas e defexas e o ápice das pétalas mais afilado, além dos lobos laterais do labelo serem subquadráticos (Pansarin & Amaral 2006). No município de Morro do Chapéu, foi coletada sobre tronco de árvores em áreas de floresta.…”