Pinguicula jackii — 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 pressed against the wet limestone. A study of a population in Cienfuegos found on average about nine leaves per plant, six of them active and the rest dying back; the area such a rosette covers ranges from barely a couple of square centimetres to well over a palm's worth. Slender scapes rise from the centre, each with a single two-lipped, spurred flower. One plant in that study carried at most seven flowers at once. Out of flower the glossy, wet-looking leaf is the recognition point.

Similar species

In central Cuba this species shares the limestone with Pinguicula lithophytica, which also grows on shaded wet limestone in the Trinidad mountains and has a white flower with a yellow throat. That is the most useful field distinction, provided you meet a flowering plant. The butterworts of eastern Cuba grow hundreds of kilometres away on serpentine and do not come into it; the western lowland species live in sand savannas, not on rock faces. Anyone finding a rosette on a dripping limestone wall in the Escambray is therefore choosing between two.

The trap and how it works

As in all butterworts the trap consists of two gland types: stalked glands with a sticky droplet and sessile glands releasing digestive enzymes once prey lies on them. On a vertical wall that works slightly differently from flat ground: the fluid tends to run off, and the leaf margin curling towards the prey holds it in place. What sticks is midges, gnats and other small fliers hanging in the humid lee of the rock face — a place where such insects gather of their own accord through the airflow.

Habitat and ecology

Vertical limestone walls with seeping water, averaging just over seventy-five degrees of slope, mostly facing north or east and so out of the fierce midday sun. The surrounding vegetation is rainforest and evergreen montane forest, together with the conical limestone hills Cuba calls mogotes. The associate lists include species such as Begonia banaoensis and Dorstenia nummularia — plants of the same wet, shaded rock niches. The studied populations range from a little over six hundred to nearly a thousand metres. For such a plant a cliff is not a uniform habitat but a patchwork: permanently dripping niches alternate with edges that dry between showers, and the rosettes follow those wet patches closely. On a wall ten metres wide the plant may therefore occupy only a few palms' worth of surface.

Distribution and elevation

Endemic to Cuba. The nominate subspecies is known from the Guamuhaya mountains in the south-central part of the island, with sites in Cienfuegos province and adjacent Villa Clara: Carso de Buenos Aires, Loma Las Lagunas, Mogote La Habanera, Vegas de Mataguá and Mundo Nuevo. The area these populations span together is measured in square kilometres and the actually occupied surface in square metres — characteristic of a plant that can only stand on suitable walls.

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 3 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

Two subspecies are recognised: the nominate form and subsp. parviflora, which as the name says has smaller flowers. Most fieldwork has been done on the nominate form in the Guamuhaya mountains; less is known about the range and variation of the other. Within a single population rosette size tracks the position on the wall closely: where water runs permanently the plants are larger than in niches that dry out between showers. Cultivated selections fall outside this account.

Where and when to see it

April is the best moment: in the studied area by far the greatest share of plants was then in flower. Search along the foot and flanks of limestone walls on north and east aspects, where water slides over the rock as a thin film and moss and liverwort stay green. Binoculars help, because many rosettes sit high on the face. Many sites lie near abandoned coffee plantations and smallholdings; keep to the paths and do not enter private ground without permission. Look also at what grows around it: where begonias and other shade-loving rock plants stand, the face is wet enough. In this landscape that is the quickest way to tell promising walls from hopeless ones.

Conservation status

The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known comes mainly from the study of the nominate subspecies in the Guamuhaya mountains: three previously known subpopulations were confirmed and one new one found, and the actually occupied area proved to be under four square metres within a range of just over thirteen square kilometres. The threats named are intensive horticulture with repeated spraying close to the walls, burning, clearance, invasive species and declining rainfall. A global category is missing; the local figures are no less serious for that.

Scientific name

Pinguicula jackii | Barnhart, 1931

Described by John Hendley Barnhart in 1931, in Addisonia 15: 61–62. The type area lies at Las Lagunas, Buenos Aires, on perpendicular, north-facing rocks at around 762 metres elevation, in what was then Santa Clara province (now Cienfuegos) in Cuba; the type material was collected in 1928 by J.G. Jack. The species name jackii honours John George Jack, whose fieldwork in Cuba provided the type material.

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