Drosera fragrans — Vorstman's Guide to the Carnivorous Plants

Identification

An annual sundew of the D. indica group: plants with an erect to scrambling stem and long, narrow leaves bearing glandular tentacles, living for a single growing season. The most striking feature is the scent of the flowers, sweet and fruity, which is absent or much weaker in related species of the group. Reliable measurements and flower colour from the original description were not available for this guide; those fields are left empty.

Similar species

The confusion lies within the D. indica group, which in northern Australia contains a series of very similar annual species, such as D. finlaysoniana, D. hartmeyerorum, D. serpens, D. aquatica and D. glabriscapa. They differ in hairiness, anther structure and seed shape. Flower scent is a useful field character in D. fragrans, but requires flowering plants and a good nose. Species of the D. petiolaris complex are easily distinguished by their rosette of long stalks with a small round blade.

The trap and how it works

An active flypaper trap along the length of the leaf. The tentacles mainly catch flying insects that blunder into the leaves or land on them. There are indications that the flower scent influences which insects visit the plant's surroundings, and thus possibly the make-up of the prey; this has not, however, been studied in detail.

Habitat and ecology

Open, sunny places in tropical savanna that become wet in the rainy season (W7), in savanna woodland (B6). As an annual it survives the dry season solely as seed.

Distribution and elevation

Endemic to northern Australia: northern Western Australia and the Northern Territory. The range description 'tropical northern Australia' fits. Precise limits and altitudinal limits are not published in the sources consulted; 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 47 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

No varieties are recognised. The species is one of many split since 2000 from the broad concept of D. indica, and belongs to section Arachnopus. Older records of 'D. indica' from northern Western Australia and the Northern Territory may therefore refer to this species.

Where and when to see it

Search in the wet season in open, wet places in savanna and smell the flowers: the sweet melon scent is the quickest way to tell this species from its relatives. Also photograph the flower and stem and note the locality; that is often needed for a firm identification within the D. indica group.

Conservation status

On the IUCN Red List the species is Least Concern (LC); it is not listed in CITES. The range lies mostly in little-developed savanna country. Local threats are changes in fire regime, grazing and invasive grasses, which close over the open wet places on which the species as an annual depends.

Scientific name

Drosera fragrans | Lowrie, 2013

Described by Allen Lowrie, in "Carnivorous Plants of Australia Magnum Opus", volume 3, p. 1271 — sources differ slightly on the year (2013 or 2014). The precise type locality could not be established. The species occurs in northern Western Australia and the Northern Territory. Named after the strong, sweet fragrance of the leaves and stem, likened to honeydew melon — the scent is thought to play a role in attracting prey.

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