Drosera erythrogyne — Vorstman's Guide to the Carnivorous Plants

Drosera erythrogyne — the trap in close-up — **The trap in close-up** · Photo: Em Lamond — CC BY 4.0 · Wikimedia Commons

Drosera erythrogyne — the flower — **The flower** · Photo: (c) Em Lamond, some rights reserved (CC BY) — CC BY 4.0 · Wikimedia Commons

Drosera erythrogyne — the habitat — **The habitat** · Photo: Em Lamond — CC BY 4.0 · Wikimedia Commons

Identification

A perennial tuberous plant that forms a new, slender stem every year. The stem scrambles or climbs through the vegetation and can reach 2 m, by some accounts 2 to 3 m. Along the stem are scattered small, shield-shaped trapping leaves with tentacles, which the plant also uses as climbing organs. The flowers are white with, as the name indicates, a red pistil, and appear from August to October. Precise leaf and flower measurements were not available in the accessible sources.

Similar species

There are several climbing tuberous sundews in the south-west, including Drosera macrantha, Drosera menziesii and Drosera pallida. The combination of white flowers with a red centre and a habitat in swamps and near granite rocks in the south distinguishes D. erythrogyne. A look at the red styles and ovary is needed for a sure identification.

The trap and how it works

An active flypaper trap that doubles as a climbing aid. The shield-shaped leaves along the stem bear stalked glands with droplets of glue. Flying insects moving between the shrubs get stuck on them; the tentacles bend towards the prey and secrete enzymes. Because the plant reaches high into the vegetation it catches different prey from the ground rosettes of related species.

Habitat and ecology

Peaty sand and gritty loam in swamps and near granite outcrops (FloraBase) (W4, R3). The plant needs shrubs or reeds to climb on. It survives the dry summer as an underground tuber; with the winter rains a new stem shoots up.

Distribution and elevation

Endemic to the south-west of Western Australia, along the south coast, according to the descriptions mainly in the coastal belt west of Albany. FloraBase lists the Esperance Plains, Jarrah Forest and Warren bioregions, in the Fitzgerald, Southern Jarrah Forest and Warren subregions.

Recorded (quarter-degree cells)

Distribution based solely on records at GBIF (Global Biodiversity Information Facility), not on TDWG regions — those are often far larger than the actual range. The light halo is the area around a record, the dark core the record itself. The darker cells are 21 quarter-degree squares in which the species has actually been recorded, from GBIF and only from records accurate to within five kilometres. They show where it has been seen, not where it occurs: an empty square means nothing. For threatened species this layer never goes finer than a whole degree, deliberately.

Forms and variation

No subspecies or varieties have been described. The species is placed in subgenus and section Ergaleium, the group of erect and climbing tuberous sundews.

Where and when to see it

September is a good month. Search swamp margins and around granite rocks in the southern coastal belt, and look not only at the ground but into the shrubs: the stems hang like threads with glistening droplets between the branches. They are best seen against the light.

Conservation status

Assessed as Least Concern (LC) on the IUCN Red List and listed as not threatened in Western Australia. Not in CITES. The southern coastal belt is relatively well protected in national parks, but swamps are sensitive to drainage and changes in fire regime.

Scientific name

Drosera erythrogyne | Marchant & Lowrie, 1992

Described by N.G. Marchant & Lowrie in 1992, in Kew Bulletin, volume 47, no. 2, p. 316 — the same publication as earlier species in this golf. The precise type locality could not be established. The species occurs along the southern Western Australian coast west of Albany, in swamps or near granite outcrops. Notably, D. erythrogyne is considered the tallest sundew species in the world, with stems up to 200 cm (exceptionally up to 310 cm). Probably from the Greek erythros ("red") and gyne ("female, pistil") — possibly referring to red styles or a reddish pistil, though this is not confirmed with a source.

World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.