Vincetoxicum hirundinaria (Asclepiadaceae) is a long-lived perennial herb that grows on exposed slopes and cliffs and prefers calcareous substrate. V. hirundinaria is highly specialised to insect pollination and the main pollinators are large flies, moths, and bees. Pollen is aggregated in pollen sacs, i.e. pollinia. Each flower has five pairs of pollinia. Pollination occurs when the pollinia are inserted into the stigmatic chambers, from which the pollen tubes grow towards the ovaries. Flowering usually starts in the middle of June and lasts until the beginning of August. The seeds ripen in early autumn. Each pod contains approximately twenty wind-dispersed seeds.
V. hirundinaria has a continental Eurasian distribution, but it also inhabits the islands and coastal areas of the middle Baltic Sea. In Finland it occurs rather frequently in the southwestern mainland and in the southwestern archipelago, including the Åland islands.
Most species of Asclepiadaceae have a late-acting self-incompatibility system, which appears to be rare in angiosperms. Some evidence has been provided for a late-acting incompatibility system in V. hirundinaria. In the archipelago populations V. hirundinaria possesses, however, a mixed-mating system, i.e. populations consist of self-fertile individuals and individuals that reproduce solely following outcrossing.
V. hirundinaria is highly poisonous to mammals and many insects, and it contains several types of alkaloids and flavonoids. In Finland, V. hirundinaria is a host to one specialist folivorous moth, Abrostola asclepiadis (Lepidoptera), and two specialist seed-feeding insects, Lygaeus equestris (Heteroptera) and Euphranta connexa (Diptera).
A. asclepiadis can be locally common, but its populations rarely reach high densities. The female moth oviposits on leaves in June and July. Eggs hatch approximately ten days after oviposition. The five larval instars are completed in about five to six weeks. The lygaeid bug, L. equestris, is both a pre- and postdispersal seed predator. The adults and larvae of L. equestris feed on green ovulae, and developing and mature seeds. The oviposition period is rather long, with a peak in mid-June; this is also the main flowering period for V. hirundinaria. Although L. equestris prefers V. hirundinaria, it is able to use few other plant species/families as host plant. The main predispersal seed predator is the larva of the tephrid fly Euphranta connexa (Tephritidae). The larvae live in the developing pods, feeding on the soft seeds.
This page was updated 1.9.2011