Cypripedium wardii (Orchidaceae) employs pseudopollen with both reward and deception to attract both flis and bees as pollinators

Flowering plants always attract animals providing rewards or deceptive signals to gain reproductive success. However, there is no well-documented reporting about a pollination mechanism with both rewards and deceptive signals by a same object. We found Cypripedium wardii flowers seem to attract visitors by the white pseudopollen-like trichomes on labella in our preliminary field observation. To explore the pollination mechanism of Cypripedium wardii, especially, the ecological function of the pseudopollen-like trichomes, we conducted field observations, analyses of the traits of visitors and flowers, and breeding system experiments. The white trichomes composed by multicellular moniliform hairs on the floral labella played a crucial role to attract pollinators, causing a high natural fruit set ratio in C. wardii. We established the direct connection of the white trichomes and real pollen. We propose that flowers of C. wardii provide pseudopollen to attract suitable bees and hoverflies as pollinators. And our evidence indicate that the pseudopollen owns both deceptive and rewarding ecological functions. Our study provide a clear pollination mechanism with both rewards and deceptive signals by a same object in angiosperm for the first time. However, an inbreeding depression seem to be caused by this strategy. And we speculated that the pollen mimicry strategy with both rewarding and deceptive functions in C. wardii may be an adaptation to the habitat fragmentation of this species to gain a reproductive assurance. Keywords: bee pollinators, Cypripedium, deception, hoverfly pollinators, inbreeding depression, orchid, pseudopollen, reward

Reproductive strategies of the Macroptilium lathyroides (Papilionoideae: Phaseoleae) explain the success of ruderal species in anthropized environments

Ruderal plants are important they are used for animal (e.g., beekeeping/pasture) and human food. Many of these plants present multiple reproductive strategies that ensure that they remain in disturbed environments. Therefore, we investigated the sexual reproduction and regeneration by regrowth of the forage ruderal Macroptillium lathyroides in an anthropized area to support management of this species after cutting or grazing and determine its requirements for seed production and conditions for commercial use. We assessed the occurrence of reproduction through regeneration and species dependence on pollinators. M. lathyroides has an axial underground system capable of regrowth but not propagation post-cut. Its flowers last about eight hours and are papilionate, asymmetrical, hermaphrodite, nectariferous, vinaceous and diurnal. They present secondary pollen that is transferred to the trichomes of the style. The species is self-compatible and presents spontaneous self-pollination. The small bee Exomalopsis cf. auropilosa, was the only pollinator since it activated the brush-type pollination mechanism while gathering nectar/pollen. The species depends on seeds to propagate or maintain a seed bank, since all plants do not regrow after cutting. Thus, sexual reproduction is necessary, but pollinators are not since it is not pollinator independent.

An ancient push-pull pollination mechanism in cycads

Most cycads engage in brood-site pollination mutualisms, yet the mechanism by which the Cycadales entice pollination services from diverse insect mutualists remains unknown. Here, we characterize a push-pull pollination mechanism between a New World cycad and its weevil pollinators that mirrors the mechanism between a distantly related Old World cycad and its thrips pollinators. The behavioral convergence between weevils and thrips, combined with molecular phylogenetic dating and a meta-analysis of thermogenesis and coordinated patterns of volatile attraction and repulsion suggest that a push-pull pollination mutualism strategy is ancestral in this ancient, dioecious plant group. Hence, it may represent one of the earliest insect/plant pollination mechanisms, arising long before the evolution of visual floral signaling commonly used by flowering plants.

Author Correction: De novo assembly of the Platycladus orientalis (L.) Franco transcriptome provides insight into the development and pollination mechanism of female cone based on RNA-Seq data

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

PREDATOPHILY- A NEW POLLINATION MECHANISM REPORTED IN WESTERN GHATS

Predatophily – a new pollination mechanism has been described from Impatiens, Sonerila and Strobilanthes species in the Western Ghats of India.