Heliamphora arenicola

No photograph of this species under a Creative Commons licence or in the public domain is in the guide yet.

Identification

A small, squat rosette of erect pitchers, each formed from a single leaf grown shut into a funnel with a seam down the front. The pitchers reach about 18 cm; in the most open, sun-exposed places the plants stay below even that and look scorched and compressed. The colour is a bright yellow-green — chartreuse — that stands out sharply against the white sand the plant sits in. On the back rim stands the nectar spoon, here vivid red and conspicuously small in proportion to the pitcher; that proportion is one of the characters by which the species was recognised. The rest of the build is the genus standard: no broad hood over the mouth, but an upward-widening funnel with a smooth zone below the rim. Measurements of the flowers and the scape are not recorded for this species in publicly accessible sources.

Similar species

Two species on and around the same massif come into consideration first. Heliamphora elongata, of Ilú-tepui itself, has clearly longer, slenderer pitchers and grows higher on the mountain. Heliamphora nutans, the species of the Roraima group further along the eastern tepui chain, is larger and darker. Heliamphora arenicola is separable from both by the combination of squat growth, bright yellow-green colour and the proportionally small red spoon — and above all by where it stands: find a Heliamphora in white quartz sand on a slope below the plateau rather than in peat on the summit, and in this area it is almost certainly this species. Confusion with Sarracenia is ruled out geographically.

The trap and how it works

A pitfall trap of the simple, open kind that marks the genus. The nectar spoon on the back rim is the lure: a nectar-like substance is secreted there, and the insect that comes to it stands directly over the mouth. In this species that spoon is small, which makes the trap no less effective but does make it less conspicuous. The upper zone of the inner wall carries downward-pointing hairs, so climbing back out fails; below that the wall is smooth. Digestion in this genus is left largely to bacteria in the pitcher fluid, after which the plant takes up the released nutrients. In a soil of nearly pure quartz sand, where practically no nitrogen or phosphorus is available, the trap is here even more emphatically the main supply than in the peat of the plateaus.

Habitat and ecology

Sandy, seeping ground on the western slopes and in the foothills of the massif: seepage bogs over sand where water runs permanently down out of the mountain (W3), on a floor of pure white quartz sand or sand with only a trace of organic matter (D2). The plant stands in open, sun-exposed places among Stegolepis and low grasses, not in shelter. Although the site lies below the plateau rim, this is unmistakably table-mountain country: the same leached sandstone, the same continual rain, the same extreme poverty (R4). The combination of full sun, a permanently wet footing and a soil without nutrients explains both the size of the plant and the fact that it faces almost no competition here.

Distribution and elevation

Known from the western side of the Ilú–Tramen massif in the Gran Sabana, Bolívar state, Venezuela — the northernmost massif of the eastern tepui chain, close to the Guyanese border. There are indications that the species also occurs on Karaurín-tepui, but that has not been established with certainty. The sites lie below about 2000 m; the type material was collected at around 1500 m, low for this genus. The genus as a whole is confined to the table mountains of the Guiana Shield — Venezuela, western Guyana and the far north of Brazil. That this species grows on the flank rather than the summit makes it an outlier within that pattern: it occupies a setting that on most tepui slopes has been taken by forest or savannah.

• Native

Forms and variation

No varieties or forms have been described for this species, and no natural hybrids either. The latter is notable, since nearby mountains do hold species of the genus with which crossing would be conceivable; the separation in altitude and in substrate — sand on the slope against peat on the summit — appears to act as the barrier. There is variation within populations in size and in how far the pitcher flushes red, depending on exposure, but that variation has no taxonomic name. The species was described only in 2011 and the number of populations examined is small, so wild variation here is still largely unmapped ground. Further fieldwork on the surrounding slopes may well bring more differences to light.

Where and when to see it

The Ilú–Tramen massif lies in the Gran Sabana and is reached on foot from the Pemón villages in a few days, with local guides; the slopes where this species stands are met on the way up rather than at the top. Search the sand, not the peat: watch for open, level patches where white quartz sand comes to the surface and water seeps permanently through it, among low grasses and the stiff leaf-tufts of Stegolepis. The plants are small and are easily lost in that vegetation; the vivid red spoon gives them away sooner than the pitcher itself. The flowering period of the species is not established in the literature.

Conservation status

The species has not been assessed for the IUCN Red List, and there is no CITES listing: Heliamphora appears in no appendix. What can be said is that the known range is very small — effectively one mountain flank, with an unconfirmed second site — and that the species is besides tied to a particular and local substrate, which fragments that range further. Against that, the area forms part of a national park, the slopes are reachable only on foot and with a guide, and there is no indication of decline. Collection for trade is the risk usually named for the genus; material in cultivation now comes almost entirely from seed and tissue culture. The absence of a formal assessment follows from the youth of the name and the small amount of fieldwork: it is a gap, not an established decrease.

Scientific name

Heliamphora arenicola | Wistuba, Fleischmann, Nerz & McPherson, 2011

Described by Andreas Wistuba, Andreas Fleischmann, Joachim Nerz and Stewart McPherson in 2011, in the book “Sarraceniaceae of South America” (Redfern Natural History Productions, Poole). The type area lies on the western side of the Ilú-Tramen massif in Venezuela's Gran Sabana, at elevations up to 2000 metres. The species name arenicola combines the Latin arena ("sand") and -cola ("dweller") and refers to the species' sandy habitat.

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