Drosera hookeri — Vorstman's Guide to the Carnivorous Plants

Drosera hookeri — the flower — **The flower** · Photo: MFdeS — CC BY-SA 3.0 · Wikimedia Commons

Identification

A small perennial 5 to 10 cm tall that grows in winter from a white tuber lying 2 to 5 cm below the surface. The whole plant is yellow-green to distinctly yellow, even in full sun. There is a well-developed rosette of crescent-shaped leaves on the ground, and several repeatedly branched stems often arise from the base, carrying peltate, crescent-shaped trapping leaves. The white flowers appear close to the basal rosette; the petals are 4 to 4.5 mm long and the sepals carry only short, sparse hairs. The seeds are cylindrical, 0.6 to 0.7 mm long.

Similar species

Within the complex Drosera gunniana is the main look-alike: it is larger (8 to 30 cm or more), usually has one dominant main stem, pink to red tubers, densely hairy sepals with hairs over 0.8 mm and larger pink or white petals 5 to 8 mm long. D. peltata in the strict sense is slender, reddish and has densely hairy calyces; D. auriculata has glabrous sepals. The bright yellow-green colour and the low habit, branched from the base, are good field characters.

The trap and how it works

An active flypaper trap. The peltate leaves along the stems and the crescent-shaped rosette leaves carry tentacles that catch small insects in sticky mucilage; the marginal tentacles bend towards the prey, after which the shorter central tentacles digest it. Because of the low habit, the catch consists mainly of crawling and low-flying insects among the grass.

Habitat and ecology

Grassland and grassy woodland that is wet in winter and dries out in summer (W7, B6), on the coast, on the tablelands and inland. According to De Salas it grows mainly in damp, open grassland, whereas D. gunniana favours heathy and grassy woodland. The plant survives the dry summer as a tuber and often grows alongside other species of the complex.

Distribution and elevation

South-eastern Australia: Tasmania (where the type comes from), Victoria and South Australia, and according to some sources also New South Wales. Sources conflict about New Zealand. Gibson and colleagues included plants from northern New Zealand in this species, but according to the New Zealand Plant Conservation Network these have belonged to D. gunniana since 2018. The 'and New Zealand' in the range description is therefore uncertain. Altitudinal limits are not precisely published; the elevation field is left empty.

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 184 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

Growers in Victoria distinguish a lower form branched from the base and a taller form with a single green stem. That taller form may fall (partly) within D. gunniana as delimited in 2018. The sources do not yet agree on the exact boundary between the two species. Anyone using older records should bear in mind that 'D. hookeri' from before 2018 sometimes also includes D. gunniana.

Where and when to see it

Search in the Australian spring in damp, open grassland and grassy woodland, for example in central Victoria and Tasmania. The bright yellow to yellow-green plants stand out among the grass precisely because of their colour. Take a hand lens to examine the calyx. Do not dig up tubers; they lie surprisingly deep and the plant needs them to get through the summer.

Conservation status

On the IUCN Red List the species is Least Concern (LC); it is not listed in CITES. That assessment probably follows the pre-2018 delimitation, which included plants of D. gunniana. Native grasslands and grassy woodlands are among the most reduced ecosystems of south-eastern Australia, so the species is locally vulnerable to conversion to farmland, building and invasive grasses.

Scientific name

Drosera hookeri | Gibson, Conn & Conran, 2010

Described by R.P. Gibson, B.J. Conn & Conran in 2010, in Journal of the Adelaide Botanic Garden, volume 24, p. 41 (20 December 2010) — a replacement name: the taxon had already been recognised in 1848 by Joseph Dalton Hooker as "Drosera foliosa Hook.f. ex Planch.", but that name was invalid (a later homonym of D. foliosa Elliott, 1824), requiring a new name. Holotype collected in Tasmania; the species overall occurs across south-eastern Australia (Victoria, New South Wales, South Australia) and New Zealand, within the D. peltata complex. Named in honour of Joseph Dalton Hooker, who first recognised the taxon.

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