Heliamphora exappendiculata — Vorstman's Guide to the Carnivorous Plants

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

Identification

A rosette of pitchers, each formed from a single leaf grown shut into a funnel with a seam down the front. Two things stand out. First the back rim: where related species carry a distinct stalk bearing a hooded spoon, here the nectar organ is withdrawn into the pitcher apex itself, so that from outside it is barely or not at all visible as a free projection — at a distance the rim simply seems to close over. Second the mouth: it is strikingly flat and broadly spread rather than rising at an angle, which gives the pitcher an open, almost dish-like look from above. Otherwise the plant is an ordinary Heliamphora: the pitcher wall widens towards the top, the colour runs from yellow-green in shade to red in full light, and the inflorescence is a one-sided raceme on a long scape with nodding flowers. In the field, when in doubt, look at that one point above the mouth.

Similar species

The species shares its mountains with relatives it can genuinely be confused with, which makes it harder than most. Heliamphora pulchella, of the same Chimantá massif, does have a nectar spoon, broadly attached, and a densely hairy pitcher interior. Heliamphora huberi, also of Chimantá, carries a clearly free-standing spoon. Heliamphora heterodoxa, of which this plant long counted as a variety, has a normally developed appendage and grows elsewhere besides. The difficulty lies not in the species themselves but in the hybrids: where exappendiculata stands together with pulchella or huberi, plants occur with a half-reduced spoon, and those cannot be placed with certainty in the field. Then look at the site: a plant on a dripping rock face is more likely this species than a plant in open bog.

The trap and how it works

A pitfall trap that obtains food in two ways. The usual route is that of the whole genus: micro-organisms in the pitcher fluid break down captured insects and the plant takes up the nutrients released, since it produces hardly any digestive enzymes of its own. But the flatly spread pitcher mouth does something else as well. It works as a landing platform on which material falling from above comes to rest: leaf litter, twigs and insects dropping out of the surrounding vegetation. Especially on the shaded rock faces, where the plants stand beneath overhanging growth, the pitcher fills with organic detritus that yields nitrogen just as well once broken down. The same strategy is known from Heliamphora ionasi. A drainage slit in the wall keeps the fluid level constant, which is no superfluous provision in a place where water runs over the rock day in, day out.

Habitat and ecology

Two very different situations. The more striking is the wet rock face (R1): steep gorge walls and ravines, often near waterfalls, where seepage keeps the stone permanently wet and the plants grow literally on the rock, with little more than a skin of moss and detritus to hold on to. The species also occurs on the summits themselves (R4), in open savannah-like vegetation and low scrub on the plateau. Both environments are extremely nutrient-poor and all but permanently wet; the massifs lie in cloud for much of the day. The preference for shaded, vertical places sets this species apart in the field from most of its relatives, which are more at home in open bog.

Distribution and elevation

Endemic to Bolívar state, Venezuela, on two neighbouring table-mountain complexes: the Aprada massif, with Aprada and Araopán tepuis, and the larger Chimantá massif, where the species is known from several component tepuis including Apacará, Akopán, Amurí, Churí and Toronó. Sites lie roughly between 1700 and 2100 m. The genus as a whole is confined to the table mountains of the Guiana Shield. Within that region the Chimantá massif is an outlier: it consists of a great many adjoining plateaus and holds more species of the genus than any other mountain, which is exactly why the chance of species meeting and crossing is high there.

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 square is the only one-degree cell — 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. It shows where the species has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No varieties have been described since the plant was raised to species rank; the original name Heliamphora heterodoxa var. exappendiculata is now of historical interest only. Plants do differ noticeably from mountain to mountain in pitcher shape and in how far the mouth is flattened, without names having been given to those differences, and there is the usual colour variation between green plants in shade and red plants in light. More important is crossing in the wild: natural hybrids are known with Heliamphora pulchella and with Heliamphora huberi, both on the Chimantá massif, where the species come within a short distance of one another. Those hybrids are intermediate in the structure of the nectar organ and are in practice the largest identification pitfall around this species.

Where and when to see it

The massifs are reachable only by helicopter or on a multi-day trek with a guide, and lie in protected territory. Do not search the open plateau first but the edges of gorges and the surroundings of waterfalls: there the plants hang on wet walls, often in company with mosses and liverworts, and there the species is at its most recognisable. Take the time to view a single pitcher from the side against a pale background; the absence of the spoon is a negative character and so is only reliable when you see it clearly. If Heliamphora pulchella or huberi grows nearby, reckon with hybrids. The flowering period 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. The picture here is more favourable than for many relatives: the species occurs on two massifs and, within the Chimantá complex, on several plateaus, which by the standards of this genus makes its range a wide one. The habitat works in its favour too, since steep wet rock faces are poorly accessible and therefore all but out of reach for collectors. Collection for trade is named as a risk for the genus, but material in cultivation now comes almost entirely from seed and tissue culture. The absence of a formal assessment reflects the research backlog in the Pantepui region rather than any established decline.

Scientific name

Heliamphora exappendiculata | (Maguire & Steyermark) Nerz & Wistuba, 2006

Originally described under a different taxon by Bassett Maguire and Julian Steyermark; published as the distinct species Heliamphora exappendiculata by Joachim Nerz and Andreas Wistuba in 2006, in Carnivorous Plant Newsletter 35(2): 43–51. The type area lies on the Chimantá and Aprada massifs in Bolívar state, Venezuela. The species name exappendiculata combines the Latin ex ("without") and appendicula ("small appendage") and refers to the absence of the small nectar spoon found in related species.

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