Drosera helodes — Vorstman's Guide to the Carnivorous Plants

Drosera helodes — the flower — **The flower** · Photo: User:Denis Barthel — CC BY-SA 3.0 · Wikimedia Commons

Identification

A small, fibrous-rooted, perennial rosette reaching about 8 cm tall; as in many pygmy sundews the rosette can rise over the years on a short stem. At the heart of the rosette sits a tuft of shiny, whitish stipules, the hallmark of the whole pygmy group. The flowers are pink and appear in October and November. We did not find precise measurements of leaf and flower in any source consulted.

Similar species

South-west Australia holds dozens of pygmy sundews, and many cannot be named without flowers. From the orange-flowered species, such as Drosera hyperostigma and D. leucoblasta, D. helodes is told apart by its pink flowers. Among the pink- and white-flowered species the differences often lie in details of styles, stigmas and the hairiness of scape and sepals, visible with a hand lens. The wet coastal-plain habitat is a clue, not proof.

The trap and how it works

An active flypaper trap in miniature. The leaf blades carry stalked glands each with a sticky droplet; the outer, longer tentacles catch the prey and then bend towards the centre of the leaf, where shorter glands take over the digestion. The prey is the very smallest: springtails, mites, tiny midges. For so small a plant every catch is a real contribution to its nitrogen supply.

Habitat and ecology

Sandy soils with laterite in hollows that are wet in winter and dry out in the long, dry summer (W7, D3, D1). The plant grows through the wet winter and spring months, flowers in spring and withdraws in summer to a resting bud protected by the stipules.

Distribution and elevation

Endemic to south-west Australia. FloraBase records the species for the Swan Coastal Plain bioregion, in the Dandaragan Plateau and Perth subregions: the coastal plain around and north of Perth.

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 5 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 or varieties have been described. As in nearly all pygmy sundews, the plant reproduces not only by seed but also asexually: at the end of the growing season it forms gemmae in the heart of the rosette, small modified leaves that are flung away by splashing raindrops and grow into new plants. That is why they often stand in dense little groups.

Where and when to see it

Go in October, when the flowers are open; they only open in sunshine, so choose a bright day around midday. Search the edges of wet hollows on the coastal plain and kneel down: a rosette a few centimetres across only shows up when you are right above it. Much of the remaining bushland on the coastal plain is hemmed in by suburbs; keep to the paths.

Conservation status

On the global IUCN Red List the species is listed as Least Concern (LC), and in Western Australia it is also regarded as not threatened. It is not listed in CITES. Its habitat does lie in one of the most urbanised parts of south-west Australia, where wet hollows are drained and built over. Uncertainty: the available sources are thin; we could not consult the original description or the detailed treatment in Lowrie's Carnivorous Plants of Australia Magnum Opus (2013).

Scientific name

Drosera helodes | Marchant & Lowrie, 1992

Described by N.G. Marchant & Lowrie in 1992, in Kew Bulletin, volume 47, no. 2, p. 324 (29 June 1992). On Great Northern Highway, about 3 km north of Bullsbrook, Central Rural District of Western Australia. Collected by A. Lowrie on 22 November 1983 (field no. 83/045); holotype PERTH 4179226. Probably from the Greek helōdēs ("of marshes, marsh-loving") — consistent with the species' habitat in winter-wet depressions, though this is not literally confirmed in a source.

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