Drosera oblanceolata — Vorstman's Guide to the Carnivorous Plants

Identification

A perennial, flat to semi-erect rosette of oblanceolate leaves: the blade tapers gradually to the base without a sharply defined petiole and carries red tentacles on the upper surface and along the margin. The scapes rise from the centre of the rosette and carry a one-sided raceme of a few flowers. No reliable source for measurements and flower colour could be consulted for this guide — the original description and the treatment in the Flora of China were not accessible — so the size fields are left empty.

Similar species

The most obvious confusion is with Drosera spatulata, which occurs in the same area and has a spatulate blade on a shorter, more clearly defined stalk; D. oblanceolata has longer, narrower and more gradually tapering leaves. Southern China also has D. burmannii, with a flat rosette of short wedge-shaped leaves and five styles, and D. peltata, which forms an erect stem with peltate leaves. According to the authors of D. ultramafica, D. oblanceolata is also related to that species and to D. neocaledonica; their ranges do not overlap.

The trap and how it works

An active flypaper trap. The red tentacles on the blade each carry a droplet of sticky mucilage; a small insect landing in it is held, after which the tentacles bend towards the prey. The glands secrete enzymes and absorb the released nutrients. With rosettes of this size the catch is mainly small midges, flies, ants and springtails.

Habitat and ecology

In Hong Kong the species grows on wet, open spots on hillsides: on damp rocks and bare ground with seeping water, along stream banks and in wet, open grassland and marsh vegetation (R1, W4). The ground is always acid, nutrient-poor and well lit. More detailed habitat descriptions from the original literature could not be consulted for this guide; the codes give the general picture.

Distribution and elevation

Southern China: Hong Kong, where most documented records come from, and scattered in Guangdong, Guangxi and Fujian. The species is not known outside China. No published altitudinal range was found; the elevation field is left empty.

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

No varieties are recognised. The species belongs to the difficult group around D. spatulata, in which several closely related species have been described in recent decades. Not all authors agree whether D. oblanceolata is an independent species or falls within the variation of D. spatulata; Plants of the World Online accepts it as a species.

Where and when to see it

Search in the wet season, from late spring into summer, on open, wet hillsides with seepage, along the trails of Hong Kong's country parks. The rosettes are small and often lie among moss and grass; look where water runs over the ground or over small rocks. Keep to the paths, because these wet spots are small and easily trampled.

Conservation status

The species has not been assessed for the global IUCN Red List and is not in CITES. Its known range is small and lies in one of the most densely populated parts of the world; urbanisation, road building and changes in drainage are plausible threats. In Hong Kong some of its sites lie within protected country parks.

Scientific name

Drosera oblanceolata | Ruan, 1981

Drosera oblanceolata was described in 1981 by the Chinese botanist Y.Z. Ruan, in Acta Phytotaxonomica Sinica, volume 19(3), p. 340, with an accompanying figure (fig. 1). The species is known from China (including Hong Kong and adjoining coastal provinces). The precise type locality (province), collector and collection date could not be established with certainty. The name is descriptive botanical Latin: the prefix "ob-" ("reversed, inverted") combined with "lanceolata" ("lance-shaped") gives "oblanceolate", referring to the shape of the leaf blade, which is lance-shaped but broadest near the tip rather than near the base.

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