Drosera dichrosepala — Vorstman's Guide to the Carnivorous Plants

Drosera dichrosepala — the trap in close-up — **The trap in close-up** · Photo: Denis Barthel — CC BY-SA 3.0 · Wikimedia Commons

Drosera dichrosepala — the flower — **The flower** · Photo: Kevin Thiele from Perth, Australia — CC BY 2.0 · Wikimedia Commons

Identification

A perennial, fibrous-rooted pygmy sundew with a small rosette no more than 1.5 cm across; with its flowering stem the plant reaches 4 cm. At its heart stands the cone of silvery stipules that protects the plant as a resting bud in summer. The flowers are white to pink and appear in September and October. The feature giving the species its name is the sepals, which show two colours. Precise leaf measurements were not available in the accessible sources.

Similar species

The closest relative is Drosera enodes, treated by Schlauer as a subspecies of D. dichrosepala and elsewhere as a species; D. enodes grows on wet, peaty soil and at swamp margins, while D. dichrosepala grows on drier sand and laterite. Other white- or pink-flowered pygmy sundews, such as Drosera closterostigma and Drosera eneabba, are told by stigma shape, stipules and calyx. The two-coloured sepals are the most practical feature.

The trap and how it works

An active flypaper trap. The small leaves bear stalked glands with droplets of glue in which small animals such as springtails, mites and minute flies are caught. The tentacles then bend towards the prey and secrete digestive enzymes. The rusty colour alluded to in the English name comes from the red glands and the reddened leaves in sunlight.

Habitat and ecology

White to grey or red-brown sand and rocky laterite (FloraBase), in open heath and open woodland of the interior (D1, D3). The ground is moist in winter; in summer it dries out and the plant rests.

Distribution and elevation

Endemic to the south-west of Western Australia. FloraBase lists the Avon Wheatbelt and Jarrah Forest bioregions. Because the species is listed as endangered on the IUCN Red List, this guide gives no more precise localities.

Recorded (one-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 6 one-degree squares — roughly a hundred and ten kilometres — in which the species has been recorded, from all GBIF records. This is coarser than for most species because hardly any record of this plant carries an accurate coordinate: the locality of poached species is obscured at source. At this scale that obscuring disappears into the noise. The cells show where it has been seen, not where it occurs: an empty square means nothing.

Forms and variation

Two taxa are placed under the name: subsp. dichrosepala and subsp. enodes. The latter was described as a species by Marchant and Lowrie in 1992 and reduced to a subspecies by Schlauer; FloraBase carries both views. An older name, Drosera scorpioides var. brevipes, is a synonym. Like all pygmy sundews the species forms gemmae in autumn.

Where and when to see it

Search in September and October in open patches of sand or lateritic gravel in the jarrah forest and Wheatbelt reserves. Bring a hand lens for the sepals. Because the species is endangered, the rule applies doubly here: keep to paths, collect nothing and do not share location data publicly.

Conservation status

The IUCN assesses the species as Endangered (EN). Remarkably, FloraBase lists it as not threatened in Western Australia; the two assessments therefore disagree, possibly because they use different species concepts (with or without D. enodes). Not in CITES. Threats to this kind of habitat in the south-west include clearing, gravel and bauxite extraction and changes in fire regime.

Scientific name

Drosera dichrosepala | Turczaninow, 1854

Described by Nikolai Turczaninow in 1854 (sometimes cited as published in 1855), in Bulletin de la Société Impériale des Naturalistes de Moscou, volume 27, no. 2, p. 343. The precise type locality could not be established. The species occurs in south-western Australia, north of Albany, around Mount Barker. From the Greek dis ("two") and chroia ("colour") plus the Latin sepalum ("sepal") — refers to the plant's two-coloured sepals.

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