Notes on the self-pollination in Dendrobium biflorum (Orchidales, Dendrobiinae)

Abstract

The conditions favouring self-pollination are determined for a species of <em>Dendrobium </em>Sw. A survey of gynostemium micro­morphology in collected flowers of <em>Dendrobium biflorum </em>revealed two stages of a unique form of autogamy: on germination of pollen tetrads, pollen tubes reached the stigmatic region without the pollen being displaced from the anther locules. This is the first time for this type of autogamy to be reported in <em>Dendrobium biflorum</em>. Pollen grains germinated directly from the locules, bypassing the stigma or falling or sliding down onto the stigmatic surface. The pollen tubes were long and reached the stylar canal. On The Society Islands, differences in exposure of the habitats to weather conditions and altitude gradients influence both composition and form of the vegetation, as well as the occurrence of pollinators. The form of autogamy described here may be the usual method of pollination found on The Society Islands (and even the whole of French Polynesia), where suitable pollinators are absent and/or growth conditions stressful

Biogeographical diversification of mainland Asian Dendrobium (Orchidaceae) and its implications for the historical dynamics of evergreen broad‐leaved forests

“…Although few studies have focused on the roles of mycorrhizal fungi and the pollinators of this genus, recent results have indicated a low specificity of mycorrhizal fungi in some species of Dendrobium and in epiphytic orchids more generally (Xing et al ., ). Moreover, while several pollination mechanisms have been illustrated in Dendrobium , including autogamy, deceptive pollination and possible sleeping site rewards (Brodmann et al ., ; Kowalkowska & Margonska, ; Pang et al ., ), it seems that most Dendrobium species rely on deceptive pollination (van der Cingel, ; Jersáková et al ., ), which indicates that EBLFs provide rewards for deceived pollinators. The habitat of Dendrobium , is therefore likely crucial for supporting Dendrobium and their pollinators.…”

Micromorphology of Labellum in Selected Dendrobium Sw. (Orchidaceae, Dendrobieae)

“…This may be due to a lack of suitable pollinators or stressful growing conditions in that area. However, it is not determined whether autogamy would also occur in these taxa outside the mentioned study area [ 28 ].…”

A novel case of autogamy and cleistogamy in Dendrobium wangliangii: A rare orchid distributed in the dry‐hot valley

“…No effective pollinator was observed in our investigation. Most Orchidaceae species exhibit particular types of floral morphology, color patterns, fragrances, or rewards for cross‐pollination; thus, the tendency of automatic self‐pollination is reduced (Kowalkowska & Margońska, ). However, automatic self‐pollination within Orchidaceae is a rather common mode in windless, drought conditions, and insect‐limited habitats (Liu et al, ).…”

“…Orchidaceae species exhibit particular types of floral morphology, color patterns, fragrances, or rewards for cross-pollination; thus, the tendency of automatic self-pollination is reduced (Kowalkowska & Margońska, 2012). However, automatic self-pollination within…”

“…However, not all orchids possess adaptations that guarantee cross-pollination, and some have become modified to ensure self-pollination. Autogamy is the preferred mode of pollination and is a rather common phenomenon within the orchid family (Kowalkowska & Margońska, 2012). Between 5% and 20% of orchid species have evolved autogamy (Gale, 2007;Pang et al, 2012;Tremblay, Ackerman, Zimmerman, & Calvo, 2005).…”