Drosera cayennensis — Vorstman's Guide to the Carnivorous Plants

Identification

A small, flat rosette of spatulate leaves in which the rounded blade tapers gradually into a narrow petiole. In sun the rosette turns red, in shade greener. The scapes are thin, coiled at the tip, and carry a few pink flowers that open one after another. No reliable set of measurements that certainly applies to this species was found; the size fields are left empty.

Similar species

Separating it from close relatives is the big problem. Drosera capillaris, from the south-eastern United States through Central America and the Caribbean to northern South America, looks almost identical; so does Drosera communis in Brazil, and Drosera colombiana and Drosera panamensis are regarded by some as closely related or even synonymous. Characters of seed, stipules and hairs are used, but without a recent revision of the whole group field identifications remain provisional.

The trap and how it works

An active flypaper trap as in the other rosette species. The tentacles catch small insects walking over the ground or flying low, after which surrounding tentacles bend towards the prey. In the wet savannas ants and small gnats are the main prey.

Habitat and ecology

Open, acid, nutrient-poor sandy and loamy soils in wet savannas, seasonal marshes and along the edges of pools, and also disturbed wet ground such as roadsides and ditches (B6, W7, H2). The plant needs full sun and grows best where vegetation stays low and open.

Distribution and elevation

Northern South America: the Guianas, Venezuela, Colombia and northern Brazil. The area column of this guide also names the Caribbean; records from there, such as from Trinidad, are possible, but most Caribbean plants of this group are usually assigned to D. capillaris. The exact range therefore depends on the unresolved taxonomy.

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 19 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 group around D. capillaris contains several names in the Neotropics, including D. cayennensis, D. colombiana and D. panamensis, whose mutual boundaries are uncertain. Molecular work on the group is scarce, and the present arrangement rests largely on old descriptions.

Where and when to see it

In the rainy season search the open wet savannas of Suriname, French Guiana or Venezuela, and sandy tracks with boggy verges. Photograph the scape, leaf base and, if possible, ripe seed, since those characters are needed to separate the species from its relatives.

Conservation status

Not assessed for the global IUCN Red List and not listed in CITES. The species appears fairly widespread and also grows on disturbed ground, so there is no immediate cause for concern. Conversion of savanna to farmland, plantations and building land destroys sites locally, especially in the coastal belts of the Guianas.

Scientific name

Drosera cayennensis | Sagot ex Diels, 1906

Manuscript name by Sagot, validly published by Diels in 1906, in Engler's "Das Pflanzenreich", IV, family 112, p. 86. The precise type locality could not be established. The species occurs from Panama to the Guianas and Brazil, with records also from the Orinoquía region of Colombia/Venezuela, at 200-250 m elevation. Named after Cayenne, French Guiana — probably the place where Sagot, who worked extensively in French Guiana, collected the original material.

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