An experimental study of the pollination biology of the perennial halophyte Frankenia pauciflora var. gunnii (Frankeniaceae) in a South Australian salt marsh

Abstract

Relatively little is known about the pollination biology or breeding systems of entomophilous plant species in salt-marsh habitats. In the present study, the pollination biology of the perennial halophyte Frankenia pauciflora DC. var. gunnii Summerh. (Frankeniaceae) was investigated in a salt marsh near Goolwa, South Australia. The flowering peak of this species occurs in summer and flowers are visited by a diverse array of insects in the Diptera, Hymenoptera and Lepidoptera. An experiment was performed to test for the presence of pollen limitation in the field. Flowers to which outcross pollen was added produced significantly more fruits and significantly more seeds per fruit than did unmanipulated control flowers. Average seed weight per fruit did not differ significantly between control and pollen-addition flowers. In glasshouse experiments, flowers to which cross-pollen was added produced significantly more fruit than did flowers to which self-pollen was added, suggesting the presence of a facultatively xenogamous breeding system.

Are all intertidal wetlands naturally created equal? Bottlenecks, thresholds and knowledge gaps to mangrove and saltmarsh ecosystems

“…Pollen transport within and among wetlands is a function of the pollen vector. Saltmarsh species are pollinated by wind and a wide array of invertebrate pollinators, with no species known to be vertebrate‐pollinated (Pojar, 1973; Mackay & Whalen, 2009). Mangroves are almost exclusively animal‐pollinated; it was once thought that Rhizophora had the potential for wind‐pollination, but flowers within this genus produce nectar, are linked with invertebrate visitation, and lack a suitable stigma for the reception of wind‐borne pollen (Tomlinson, 1986).…”

Biotic Filters Shaping Limonium Invasion in San Francisco Bay Salt Marshes

“…Pollination syndromes of salt marsh plants are not well-studied, and the majority of marsh dominants including Salicornia and Spartina species are presumed to be windpollinated (anemophilous). Several other common but non-dominant marsh species within the genera Frankenia, Jaumea, and Grindelia are insect-pollinated (entomophilous), with bees and wasps carrying the largest pollen load 43,44 . Bumblebee and honeybees frequent flowers of both anemophilous and entomophilous marsh plants, and given particular site-specific characteristics some plants may have secondary entomophily 45 .…”

“…and Distichlis spicata) and entomophilous salt marsh plants (Frankenia pauciflora) have been shown to be pollen-limited, so pollinators may play a role in crucial (even if infrequent) pollen supplementation 43,47 . However, other than Mackay's (2009) study of Frankenia pauciflora in South Australia salt marshes, few studies have conclusively demonstrated the occurrence or effectiveness of insect-mediated pollination (i.e. transfer of pollen to stigmas) as opposed to pollen foraging.…”