Drosera sulphurea — Vorstman's Guide to the Carnivorous Plants

Identification

A scrambling perennial tuberous plant with stems 40 to 60 cm long bearing small, peltate trapping leaves. The flowers are yellow — the epithet means 'sulphur-coloured' — and appear in September. Exact leaf and flower measurements are not published in the sources consulted.

Similar species

Drosera subhirtella also climbs and flowers yellow, but stays smaller (up to 40 cm) and grows in a broader range of habitats; Lowrie regards the two as only distantly related. Drosera neesii, with which D. sulphurea was long merged, is the other obvious confusion; the difference is not worked out in the sources consulted. A coastal habitat among Cephalotus is a good clue.

The trap and how it works

An active flypaper trap, but held well above the ground. The leaves along the stem are small, peltate and often cup-shaped, with longer tentacles on the margin and shorter ones on the blade. Flying insects — midges, small flies, sometimes bees or butterflies drawn to the flowers — touch the droplets and stay hanging. The marginal tentacles then bend inwards and the blade partly closes around the prey, after which the glands secrete enzymes and absorb the dissolved nutrients. Because the traps are spread along an upright or climbing stem, the plant sweeps a much larger volume of air than a rosette on the ground.

Habitat and ecology

Sandy loam in coastal areas (D1), in heath and scrub (B5), often among Cephalotus. That company points to moist, peaty sites: the Albany pitcher plant grows along seepages and in wet hollows (W4).

Distribution and elevation

Endemic to Western Australia, in the coastal areas of the south-west. No closer range boundary is given in the sources consulted. Altitudinal limits are not published.

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 25 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

Johann Georg Christian Lehmann described the species in 1844. George Bentham reduced it to a variety of D. neesii in 1864, and N.G. Marchant merged it fully with that species in 1982. Allen Lowrie reinstated D. sulphurea as a species in 1999. Older floras may therefore list the plant under D. neesii.

Where and when to see it

September, in sunshine, when the yellow flowers are open. Search coastal heath in the south-west, especially where Cephalotus also grows — two carnivorous plants side by side. Such places are often wet and fragile; keep to paths and touch nothing.

Conservation status

Assessed as Least Concern (LC) on the IUCN Red List; not listed in CITES. The sources consulted name no specific threats. The coastal areas of the south-west are, however, under pressure from development, root rot and altered fire regimes.

Scientific name

Drosera sulphurea | Lehmann, 1844

Drosera sulphurea was described in 1844 by the German botanist Johann Georg Christian Lehmann, in Novarum et Minus Cognitarum Stirpium Pugillus, part 8, p. 43 (cited as p. 37 in some sources). The precise type locality and collection details could not be established with certainty. The species is endemic to Western Australia. The name sulphurea is Latin for "sulphur-coloured, sulphur-yellow" and refers directly to this species' sulphur-yellow flowers.

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