Drosera falconeri — Vorstman's Guide to the Carnivorous Plants

Drosera falconeri — the flower — **The flower** · Photo: Cooleyray — CC BY-SA 4.0 · Wikimedia Commons

Drosera falconeri — the trap in close-up — **The trap in close-up** · Photo: Rosťa Kracík in cultivation — CC BY 3.0 cz · Wikimedia Commons

Identification

A perennial tropical sundew with a flat rosette whose leaves lie against the ground. Mature blades are reniform, about 1.5 cm long and 2 cm wide, up to 3 cm wide in old plants; within the subgenus they are exceptionally large. The petiole is oblanceolate, about 10 mm long, glabrous above and with white hairs along the margins and beneath. The underside of the blade is clearly veined and sparsely hairy. One or two racemes, usually 8 cm long, each carry about twelve flowers on pedicels 3 to 5 mm long. The petals are white or pink, about 7 by 4 mm; the stamens are white with orange anthers, and the three white styles are much branched. In the wild the leaves turn deep red.

Similar species

Within subgenus Lasiocephala, the 'woolly sundews' of northern Australia, most species have small blades on long, narrow, often densely hairy petioles, such as Drosera petiolaris and Drosera dilatatopetiolaris. The large, flat, reniform blades and broad, short petioles make D. falconeri unmistakable. Natural hybrids with D. dilatatopetiolaris and D. petiolaris are known and intermediate; they are recognised by smaller blades and longer petioles.

The trap and how it works

An active flypaper trap. Stalked tentacles secreting mucilage line the margin of the blade, with shorter glands in the centre. An insect landing on the leaf sticks and is enclosed by the tentacles. Because the broad blade offers a large surface, the plant can handle larger prey than its relatives, and precisely that problem, that large prey can tear free, is regarded as the evolutionary pressure that elsewhere led to the snap trap of the Venus flytrap.

Habitat and ecology

Seasonally wet ground in the monsoon belt (W7, B6). At the original site along the Finniss River the species grew on calcareous, alkaline sand (measured pH 8) under tall, dense grass; elsewhere on grey silty clay. That is unusual: most carnivorous plants avoid lime. In the dry season the leaves die back and the plant survives as a bulb-like structure of tightly packed leaf bases just below the soil surface, insulated by the hard clay. White, fleshy roots serve as water stores. The first rains of the wet season break dormancy.

Distribution and elevation

Endemic to the Northern Territory, in the northern coastal region: around the Finniss River, Palmerston and Berry Springs south of Darwin, and Melville Island. Within this area it is described as not uncommon. The label 'Kimberley, Western Australia' in the base list is incorrect: as far as known the species does not occur in Western Australia.

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 subspecies have been described, but natural hybrids have. The first documented was with D. dilatatopetiolaris, informally named by E. Westphal in 1991; its seed proved viable, which is unusual in sundew hybrids, and about four recognisable forms 4 to 10 cm across occur in the wild. A second natural hybrid is with D. petiolaris. In the wild such hybrids are rare because the species prefer different soils.

Where and when to see it

The wet season, November to March, is the time to see the plant in leaf and flower; flowering falls in November and December, usually with one flower a day that stays open for a single day. Search grey clay and sandy, calcareous spots around Darwin, among the grass. In the dry season there is nothing to see above ground. Allow for heat, flooding and crocodiles near open water.

Conservation status

Assessed as Least Concern (LC) on the IUCN Red List. Not in CITES. The Darwin and Palmerston area is developing rapidly, threatening local sites, but the species occurs over a wider area. In cultivation it is regarded as difficult; the red leaf colour of wild plants is usually lost when grown under weaker light.

Scientific name

Drosera falconeri | Tsang ex Kondo, 1984

Described by Katsuhiko Kondô & Peter Tsang in 1984, in Boletim da Sociedade Broteriana, series 2, volume 57, p. 52 — the same publication in which D. dilatatopetiolaris (golf 41) was also described, part of a revision of the Petiolaris complex. Along the Finniss River, Northern Territory, Australia; originally discovered in 1980. A more precise site along the river is not known. Named after Mr Falconer, the discoverer of the species along the Finniss River; the epithet was suggested by Peter Tsang.

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