Pinguicula orthoceras — 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 flat rosette of entire, fleshy leaves with a dense glandular coat that makes the blade look wet, lying flat on damp soil or rock. From the centre rise slender scapes, each with a single two-lipped flower whose spur points straight back instead of curving. That straight spur is the reason for the name and the most usable field character — provided you meet a flower. Out of flower the plant is a small glistening rosette among mosses, barely separable from its relatives.

Similar species

The main confusion is with Pinguicula lippoldii, which grows in the same massif but lower, around five to six hundred metres, in gallery forest along streams. The shape of the spur is the distinction that matters in the descriptions: straight in this species, otherwise curved or differently proportioned in its relatives. The butterworts of the Moa massif further east also stand close to this group. So always photograph the flower from the side, with corolla tube and spur in profile. Add to that the fact that elevation is information in itself: in this massif the known finds of the various butterworts lie at clearly different levels, so a good altitude reading already narrows the candidates considerably.

The trap and how it works

The trapping apparatus is that of any butterwort: stalked glands with a sticky droplet, sessile glands releasing digestive enzymes once prey lies on them, and a stomata-free leaf skin that reabsorbs the dissolved food. As the leaf margin rolls in, a shallow dish forms in which the digestive fluid stands. At nine hundred metres in misty montane forest the air is nearly always saturated, so the droplets almost never dry out and the trap works all year round.

Habitat and ecology

The labels name only the northern flank of the central massif of the Sierra del Cristal between nine hundred and a thousand metres. That is the belt of permanently damp montane forest, where cloud runs against the slopes for most of the year and neither soil nor rock ever fully dries. For a butterwort those are classic conditions: water in abundance, light limited, and a substrate kept poor in available nutrients by the constantly percolating water. At this altitude the forest is low and gnarled, with a thick moss layer on trunks and stones; the butterworts then sit in the openings within it, where the moss is too wet to close over and bare ground shows through.

Distribution and elevation

Endemic to Cuba and known from the Sierra del Cristal in the east of the island, on the border of Holguín and Santiago de Cuba provinces — still labelled Oriente province on the old sheets. The number of documented localities is small, and the known collections go back to the fieldwork of Bisse and Köhler in the 1960s. That does not mean the species has gone, but it does mean recent published records are scarce.

Native

Distribution by region of the TDWG scheme (World Geographical Scheme for Recording Plant Distributions), from the World Checklist of Vascular Plants — the data behind Plants of the World Online. The map shows the natural range only; where the species has naturalised is given in the text. Within a region the map says nothing about where exactly the plant grows; for threatened species that is deliberate. Outlines: tdwg/wgsrpd. No GBIF records have been gathered for this species yet; once they are, that more precise layer replaces this regional map.

Forms and variation

No wild subspecies or varieties are recognised. For a species known from one mountain flank and few collections little can be said about the breadth of variation; what counts in the literature is the shape of the spur, and whether that is constant within the species must be shown by new material. The eastern Cuban butterworts are in any case a group still in motion: recent publications have added new species and shifted old boundaries.

Where and when to see it

This is cloud forest at Cuban scale: steep, waterlogged and often inside the cloud. Search the northern slope, along trails where the earth bank stays wet, at the foot of boulders and on the banks of high streams. Get low and look into the light. The Sierra del Cristal is protected land with a long conservation history; arrange access and guidance in advance, and document every find carefully — in this species especially, well-recorded new observations are valuable.

Conservation status

The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known: an eastern Cuban endemic of the highest belt of a single massif, documented by a small number of collections from the 1960s. For a plant dependent on permanently damp montane forest the chief risks are a rising cloud base in a warming climate and changes in the forest itself. The absence of a category follows directly from a thin file, which is exactly why further fieldwork is the most urgent step. A targeted campaign of revisits to the historical localities would achieve more here than any desk study.

Scientific name

Pinguicula orthoceras | Casper, 2019

Described by Siegfried Jost Casper in 2019, in Englera 35: 97, based on material collected in April 1968. The type locality lies in the Sierra Cristal, on the northern slope of the central massif, at 900–1000 metres altitude, in the (former) Oriente Province (now Holguín), Cuba. The name likely derives from the Greek orthos (straight) and keras (horn), which would refer to a straight spur — but this was not explicitly confirmed in an accessible source.

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