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Pinguicula lithophytica
The name says it: a plant that lives on stone. Pinguicula lithophytica grows on shaded, wet limestone faces in the Trinidad mountains of central Cuba, and was described only this century — from material collected as early as the 1950s and noted then simply as 'locally common on shaded wet limestone cliffs'. It is one of the two butterworts of the Guamuhaya massif, and the only one with a white flower and a yellow throat.
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 pressed against the wet limestone, densely set above with stalked glands. Slender scapes rise from the centre, each with a single two-lipped flower. The flower is white with a yellow throat — so recorded, in English, on a label from 1953 — and that is the decisive field character. Out of flower you recognise the plant by the glossy, wet-looking leaf surface among mosses and liverworts; the blade feels greasy, which is where the scientific genus name comes from. In a rock dweller the attitude of the rosette is a character too: because the plant grows against a vertical face, the leaf surface stands upright rather than horizontal, and rainwater slides over it instead of standing.
Similar species
The only serious confusion in this area is with Pinguicula jackii, which inhabits the same dripping limestone faces in the Guamuhaya mountains and locally at comparable elevations. That is exactly why flower colour is so useful: note whether the flower is white with a yellow throat, and photograph it from the side. Other Cuban butterworts do not come into it: the western species grow in lowland savanna on white sand and the eastern ones on serpentine, hundreds of kilometres away.
The trap and how it works
The leaf is a flypaper trap with two gland types: stalked glands with a clear sticky droplet and sessile glands releasing digestive enzymes once prey lies on them. On a vertical or overhanging limestone face the problem is holding rather than catching: the leaf margin rolling towards the prey keeps the digestive fluid in place instead of letting it run off down the rock. Prey consists mostly of small two-winged insects hanging in the humid lee of the face.
Habitat and ecology
Shaded, permanently wet limestone walls under a cover of low, dense forest: that is what the old labels say, and it is still the shortest description. The site is lime-rich rather than acid, and so the mirror image of the serpentine and siliceous sites of the eastern Cuban butterworts. What matters is not the lime itself but the combination: constantly seeping water that washes nutrients away, little light, and no competition from higher plants on a bare face.
Distribution and elevation
Endemic to Cuba and known from the Guamuhaya mountains in the centre of the island — the Trinidad range — with localities such as El Sopapo, Los Tornos and the limestone hills near El Naranjo, in and around Cienfuegos province. Labelled finds lie at about nine hundred metres. That is a small, coherent range in a single limestone massif, and it makes the species one of the few Cuban butterworts belonging neither to the western lowland nor to the eastern serpentine mountains. The Guamuhaya massif is a limestone island amid flatter country, with its own climate and its own set of endemics; for plants of wet rock faces it is in effect an archipelago of walls between which exchange is barely possible.
- Native
Forms and variation
No wild subspecies or varieties are recognised. What varies is size and leaf thickness according to shade and the amount of water running over the face; on the wettest, darkest spots the rosettes are largest. Because the species was formally described only recently and the description rests partly on old material, the picture of variation within it is still based on a limited number of populations.
Where and when to see it
Search north- and east-facing limestone walls where water slides over the rock as a thin film, preferably under closed forest so the face stays wet even at midday. Look at eye level and higher, not at the ground: the plants sit on the face itself, among moss and liverwort. Binoculars and raking light help. Keep off the wall — the moss mat in which the rosettes root is thin and slow to recover from trampling.
Conservation status
The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known: a central Cuban endemic of a single limestone massif, tied to a micro-habitat — shaded, permanently wet rock face — that is naturally fragmented and cannot be extended. The old labels call the species locally common, but that says something about density on a suitable face and nothing about the number of faces. Clearance of the surrounding forest, water abstraction and increasing drought are the obvious risks; a formal assessment is still missing. For anyone visiting the area a simple rule therefore applies: look, photograph and record, but do not touch the face.
Scientific name
Pinguicula lithophytica | Panfet & Temple, 2008
Described by Cristina M. Panfet-Valdés and Paul Temple in 2008, in Carnivorous Plant Newsletter 37(3): 90–93. The species is endemic to central Cuba. The name derives from the Greek lithos (stone, rock) and phyton (plant), referring to this species' rock-dwelling growth habit.
World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.