Rare plants in the Tamar Valley
by Helen Jones
Calystegia sepium
The Tamar Island Wetlands is the home of one endangered plant Lycopus australis and one listed as rare – Calystegia sepium.
According to Curtis there are about 7 species of Lycopus in the temperate regions of the northern hemisphere and 1 species endemic in Australia.
Lycopus australis
Lycopus australis (native gipsywort) is a perennial herb which grows an erect stem to about 1.5m. It is found growing either in Pragmites reed beds or between gaps in Melaleuca ericifolia forest and on the edges of wetlands. Those plants at the Tamar Island Wetlands are conveniently growing right at the edge of the boardwalk just past the second bridge. They are quite hard to find as they are among dense reeds. There is another population at the West Tamar Fitness Trail.
The proper description of the leaves is that they are lance shaped and arranged oppositely along the stem with successive pairs at right angles to each other. They are light green, coarsely toothed and between 6-12 cm long. A nice crisp description is that they look like marijuana leaves – this makes an immediate picture in most minds. The tiny white flowers cluster at the base of the leaves. Flowering time is said to be December to April but this year they were first seen at the end of January.
Calystegia sepium (great bindweed) was presumed extinct in Tasmania until March 2001, when a specimen was collected from the Tamar Island Wetlands. They are found on either side of the first section of the boardwalk after leaving the Wetlands Centre.
Curtis lists three Calystegia species: C.sepium (great bindweed) and C. soldanella (sea bindweed) are local on coastal sands. The third one is the introduced C. silvatica (also called great bindweed).
C. sepium is a riparian species found widely throughout temperate Australia. It is naturalised in New Zealand and also found in temperate regions around the world. It is a climber with extensive underground horizontal stems which have roots and slender shoots that climb over anything nearby. The heart-shaped leaves are alternate and 4-10 cm long. The introduced species, C. silvatica, is found in the same regions but it has blunt to round leaf tips.
The funnel-shaped flowers bloom during summer, opening during the day and closing at night. They are about 4-6 cm long and white, sometimes tinged with pink.
References:
- Curtis WM 1967, The Student's Flora of Tasmania, Part
3, Government Printer, Hobart.
- Threatened Species Unit – Threatened Flora of Tasmania
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