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Pergularia rostrata (R.Br.) Spreng. 1824
pronounced: per-goo-LAIR-re-uh ross-TRAH-tuh
(Apocynaceae – the oleander family)
synonym: Marsdenia rostrata R.Br. 1810
pronounced: mars-DEN-ee-uh ross-TRAH-tuh
common names: Milk Vine, Boat Vine
Pergularia is derived from the Latin pergula, usually meaning a porch in front of a house, but it can also mean a vine-arbor; rostrata is also Latin, from rostratus, having a beak; in the synonym, Marsdenia is for William Marsden (1754 – 1836), secretary to the Admiralty, orientalist, traveller and plant collector.
This is a tall robust liana, occurring in north-eastern Queensland and right down the coastal plain as far as Victoria. It is usually found in most types of rainforest and wet sclerophyll forest. It is mostly seen as a dense scrambler to about 10 m; the stems can be slightly hairy, or smooth.
The simple opposite leaves are a glossy deep mid green on the upper surface, paler below, entire, glabrous, with flat margins. They are very variable in shape: oblong-elliptic, ovate, lanceolate to almost circular, usually with an acute point, the base rounded to cordate. They range in size from about 3.5 – 13 cm long, by 2.5 – 6.5 cm wide. The petioles have a groove on the upper surface, and there are (usually) 2 colleters at the base of the lamina. The venation is prominent below. The petioles are 1 – 4 cm long. The stem and leaves exude a milky latex.
The inflorescence is umbelliform. The flowers are about 7 – 12 mm in diameter, and pale yellow. The corolla lobes are spreading, oblong-obtuse, 3 – 6 mm long. The style is much longer than the anthers. The pedicel is about 5 mm long.
The fruits are follicles, about 5 – 8 cm long by 2 – 3 cm in diameter, usually tapering at the end. They turn brown when they ripen, and split into 2 boat-shaped halves exposing numerous brown seeds, each up to about 10 by 5 mm, with a white plume of silky hairs, 1 – 3 cm long, attached to one end.
This is a food plant for the moth Fodina ostorius .
The plant is not generally eaten by livestock, but may attract them in dry times when forage is scarce. Toxins are present in leaves and stems, and the plant can be toxic to pigs, sheep and cattle, causing an unsteady gait, incoordination and collapse, with laboured respiration, a fast pulse, dilated pupils, followed by coma and death and bloating. There is no known effective treatment.
Photographs taken in the Gustav Creek vine scrub, Nelly Bay, 2013, 2014
Page last updated 13th January 2017