Drosera citrina — Vorstman's Guide to the Carnivorous Plants

Drosera citrina — the flower — **The flower** · Photo: Kevin Thiele from Perth, Australia — CC BY 2.0 · Wikimedia Commons

Drosera citrina — the habitat — **The habitat** · Photo: Jean and Fred Hort from Perth, Australia — CC BY 2.0 · Wikimedia Commons

Identification

A perennial, fibrous-rooted pygmy sundew with a small rosette, up to 4 cm tall. At its heart stands the cone of silvery stipules found in all pygmy sundews. The flowers are lemon yellow to greenish yellow, rarely white, and appear in October. Precise leaf and flower measurements were not available in the accessible sources.

Similar species

Yellow-flowered species are scarce among pygmy sundews, which makes identification easier. The closest relative is Drosera nivea, originally described as a variety of D. citrina, which flowers white. Drosera coalara, described by Lowrie and Conran in 2014, is treated in some overviews as a synonym of D. citrina; anyone finding a yellow-flowered pygmy sundew in this area should therefore bear both names in mind.

The trap and how it works

An active flypaper trap. The small leaves bear stalked glands with droplets of glue in which springtails, mites, ants and small flies become stuck. The tentacles bend towards the prey and secrete digestive enzymes. On the poor yellow sand this by-catch is an important source of nitrogen.

Habitat and ecology

Yellow sand (FloraBase), in the open kwongan heath of the sandplains (D1, B5). The sand is moist enough in winter for growth and flowering; in the hot summer the plant withdraws into its bud of stipules.

Distribution and elevation

Endemic to the south-west of Western Australia. FloraBase lists the Geraldton Sandplains and Swan Coastal Plain bioregions, with records in the shires of Dandaragan, Gingin and Moora, 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

The former variety D. citrina var. nivea is now treated as a species in its own right, Drosera nivea. Conversely, two later names, D. chrysochila and D. coalara, are placed under D. citrina in some sources. Like all pygmy sundews the species also reproduces by gemmae, which makes it popular in cultivation.

Where and when to see it

October is the month. Search the open patches of heath on the yellow sand of the sandplains north of Perth, in sunny weather around midday when the yellow flowers are open. A yellow flower less than a centimetre across above a rosette a few centimetres wide is easier to find than the rosette itself.

Conservation status

Assessed as Least Concern (LC) on the IUCN Red List (2020) and listed as not threatened in Western Australia. Not in CITES. The sandplains north of Perth are under pressure from clearing, sand extraction and expanding settlement, but there are large protected heathland areas in the region. The taxonomic boundaries with D. coalara and D. chrysochila are uncertain.

Scientific name

Drosera citrina | Lowrie & Carlquist, 1992

Described by Lowrie & Carlquist in 1992, in Phytologia, volume 73, no. 2, p. 99. The precise type locality could not be established. The species occurs in Western Australia. From the Latin citrina ("lemon-coloured") — refers to the colour of the flowers.

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