Pinguicula caryophyllacea — 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 small flat rosette of entire leaves pressed against wet stone or lying over a thin layer of moss, the upper surface densely set with stalked and sessile glands and therefore glossy and sticky. The leaf is green, flushed red-brown in strong light. Slender scapes rise from the centre, each with one two-lipped flower with a two-lobed upper lip, a three-lobed lower lip and a spur behind; the epithet refers to the pink-like impression the flower makes. Because the original description appeared in a specialist journal and little field material exists, no measurements have been entered in this guide that the reader could check against a source. The plant forms no winter bud: in a frost-free tropical mountain climate it stays in leaf all year.

Similar species

Cuba holds several other butterworts, all in the same eastern massif and all closely related: Pinguicula benedicta, P. albida, P. moaensis and P. cubensis. In the field they are told apart mainly by the flower — length, colour and above all the shape and length of the spur — and that calls for a good specimen in bloom and, frankly, for the original descriptions side by side. Out of flower almost any Cuban butterwort on serpentine is a small green rosette and the locality is the most usable datum. P. toldensis, described in 2007, has since been merged with this species: that name is now a synonym.

The trap and how it works

A flypaper trap on one of the most hostile soils there is. Serpentine and laterite hold little of what a plant needs and much of what harms it: nickel, chromium and magnesium in high concentrations, and almost no nitrogen or phosphorus. That is why carnivory is so attractive here. The leaf carries the usual two layers of gland: stalked glands holding a tenacious droplet, sessile glands releasing digestive enzymes as soon as an insect is lying on them. The margin rolls slowly over the catch so that the fluid stands still. Because the climate is wet and there is hardly a dead season, the plant catches almost year round — a slow, continuous business rather than a short peak.

Habitat and ecology

Wet, moss-covered rock and steep banks on ultramafic rock — serpentine and the red laterite formed on it — in the Nipe-Sagua-Baracoa massif (R3). The plant grows where water runs over the stone or seeps along a stream bank (R1), in the open, low vegetation that on these soils takes the place of forest. It rains much and often; cloud hangs in the hills for days and keeps the sites damp. Competition is slight, because few plants tolerate the soil chemistry.

Distribution and elevation

The species is endemic to eastern Cuba and is known only from the Nipe-Sagua-Baracoa highlands in the provinces of Holguín and Guantánamo. That differs from our own species list, which names Colombia: the reference works place this species unambiguously in the Caribbean, not in South America. The range is small even within Cuba: a few ridges and river systems, partly inside protected areas. There is no detailed distribution map to speak of; the records are scattered across a handful of sites.

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 cells are 2 one-degree squares — 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: the locality of poached species is obscured at source. At this scale that obscuring disappears into the noise. The cells show where it has been seen, not where it occurs: an empty square means nothing.

Forms and variation

No wild varieties are recognised. Such variation as the file contains is taxonomic: in 2007 P. toldensis was described from the same highlands, later proved indistinguishable from this species and is now treated as a synonym. Among the Cuban butterworts that is no exception — the species resemble one another closely, populations are small and isolated, and the boundaries between the described species have not yet settled. No natural hybrids have been described, although several species grow in the same massif.

Where and when to see it

This is not a species you meet by chance. The Cuban serpentine highlands are hard going and largely protected; visiting in practice means permission and a local guide. Anyone who gets there should search the wet flanks of stream valleys, where water runs over bare red stone under a thin skin of moss and liverwort. Look low and close to the water. Trampling these seepages is the main risk a visitor brings along, so stay on the rock and off the moss.

Conservation status

The species has not been assessed for the global IUCN Red List and is not in CITES; there is no international category. What is known does call for caution: this is an endemic of a single massif, known from few sites, in a landscape that is also economically interesting. The Nipe-Sagua-Baracoa area is one of the world's largest nickel-mining regions, and opencast working destroys precisely the ultramafic ground these plants stand on. Fire and road building play a part too. The absence of an assessment says mostly something about how accessible the area is for research.

Scientific name

Pinguicula caryophyllacea | Casper, 2004

Described by Siegfried Jost Casper in 2004, in the journal Wulfenia. The type area lies in the Nipe-Sagua-Baracoa mountains of eastern Cuba, where the species is endemic. The species name caryophyllacea derives from the genus Caryophyllus (carnation/clove) and likely refers to a resemblance of the flower or its scent to a carnation.

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