Drosera brevifolia — Vorstman's Guide to the Carnivorous Plants

Drosera brevifolia — the trap in close-up — **The trap in close-up** · Photo: Alex Abair — CC BY 4.0 · Wikimedia Commons

Drosera brevifolia — the habitat — **The habitat** · Photo: Alex Abair — CC BY 4.0 · Wikimedia Commons

Identification

A rosette lying flat on the ground, usually about 3 cm across and rarely to 5 cm. The leaves are wedge-shaped, obovate to spatulate and 7 to 16 mm long, the blade tapering gradually into a short, broad stalk; in sun the colour is deep red to reddish purple. Stipules are absent. The scape is up to about 15 cm tall and — an important character — covered in small glandular hairs. It carries one or a few flowers that are large for the size of the plant, with white to pink petals. Flowering is in spring.

Similar species

The main confusion is with Drosera capillaris, which often grows at the same sites. It is larger, has a distinct thin petiole with a round to spatulate blade, carries fringed stipules in the centre of the rosette and has a glabrous scape; it also flowers later, in summer. Small plants of D. intermedia also have a long, glabrous petiole and an upright rather than flat rosette. A flat red rosette of wedge-shaped leaves with a glandular-hairy scape therefore points to D. brevifolia.

The trap and how it works

An active flypaper trap. The glands on the upper surface and margin of the leaf each carry a sticky droplet; a small insect that lands in it is held, after which the tentacles bend towards the prey and the leaf curls slightly round it. The glands then secrete enzymes and absorb the released nutrients. Because of the small size, the catch is mainly springtails, ants, small midges and other minute animals that walk on the ground or fly low.

Habitat and ecology

Moist to wet, acid, sandy or clayey soil that may dry out in summer: open patches in pine savannas and flatwoods (B6), the edges of marshes, ponds and temporary pools (W7), and disturbed bare ground such as roadsides, tracks and scraped land (H2). The species often grows in drier places than most other carnivorous plants in the region and benefits greatly from open, bare soil after fire or disturbance. Its short-lived, prolifically seeding habit fits with that.

Distribution and elevation

In the United States from Virginia and Kentucky south to Florida and west to Texas, Oklahoma and Kansas, including Tennessee, Arkansas, Missouri, Mississippi, Alabama, Georgia and the Carolinas. Further in eastern Mexico, Belize and Cuba, and after a large gap in southern Brazil, Paraguay, Uruguay and north-eastern Argentina. How that leap to South America came about is not clear. A reliably published altitudinal range is lacking; 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 388 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. Over time, however, several names have been given to this plant, mostly from South America, that are now treated as synonyms — among them Drosera ferruginea from Uruguay, which has its own cross-reference page in this guide. Colour forms occur: plants in full sun are deep red, those in partial shade greener, and flower colour ranges from pure white to clearly pink.

Where and when to see it

Go in spring — early in the southern US — and search bare, damp patches in open pine woods, sandy tracks and roadsides. The rosettes are so small they are easily overlooked; the flowers give them away. Come on a sunny morning, because the flowers open only in sun. As the plant often dies after flowering, numbers at a site can vary greatly from year to year.

Conservation status

The species has not been assessed for the global IUCN Red List and is not in CITES. Overall it is not rare, but it is at the northern edge of its range: in Kentucky it is considered endangered and in Tennessee threatened. The main threats are the loss of open pine savannas to forestry and development, the absence of fire, and the closing-in of the bare patches on which the seedlings depend.

Scientific name

Drosera brevifolia | Pursh, 1814

Described by Frederick Pursh, described December 1813, title page 1814, in "Flora Americae Septentrionalis", volume 1, p. 211. "Sandy swamps, Georgia" — sandy swamps in Georgia, south-eastern United States. Lectotype at herbarium PH (Philadelphia). The species occurs from eastern Texas to Florida, north to Virginia. In 1834, a variety, D. brevifolia var. major Hook., was additionally described from Louisiana. From the Latin brevis ("short") and folium ("leaf") — "short-leaved", consistent with the English common names "dwarf sundew"/"small sundew".

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