Pinguicula clivorum

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

Identification

A rosette five to ten centimetres across, from a little over three centimetres in small plants, with six to seventeen thin, pale green leaves nearly two to over four centimetres long. The leaves are obovate to almost semicircular, with a rounded tip and a wedge-shaped base. Each plant carries one to eight scapes of three to ten centimetres, densely set with glandular hairs. The flower is twelve to eighteen millimetres long including the spur, white with pale violet at the base and on the upper lip, and bears a green ridge on the middle lobe of the lower lip. The spur is cylindrical, nearly four to six millimetres long.

Similar species

Other butterworts occur in these highlands, but the combination of a small white flower with pale violet tints and a green ridge on the lower lip is distinctive. Note the spur: here it is fairly short relative to the flower and sits at an obtuse angle to the corolla. Other Central American species generally have distinctly purple or larger flowers and longer spurs. Because the species is seen so rarely, every find is worth documenting — with photographs of the flower in profile, of the lower lip and of the whole rosette.

The trap and how it works

The rosette catches with the usual two-part glandular coat: stalked glands bearing a sticky droplet and sessile glands releasing digestive enzymes once prey lies on them, after which the dissolved food is absorbed through the leaf skin. The leaves here are membranous and thin, which suits a plant of cool, damp slopes with a short growing season. At nearly three thousand metres the supply of small insects is confined to the warmest hours of the day, and the plant is accordingly most active in the wet season.

Habitat and ecology

Very steep slopes and the edges of ravines, on limestone or calcareous soil, with pine forest as surrounding vegetation; herbarium labels also describe grassy slopes with oaks. The sites lie high in the mountains, in a belt where nights are cold and mist regularly reaches the ground. These are places where the soil is thin and quickly leached, and where the plant stands on bare, steep ground too unstable for taller vegetation. Unstable slopes like these are an opportunity for small plants: every slip exposes bare, lime-rich ground on which seedlings have a head start over anything slow to root. The other side of it is that a population can slide away with the slope, or vanish.

Distribution and elevation

The known range lies in western Guatemala — Huehuetenango department, in the Sierra de los Cuchumatanes around San Juan Ixcoy and Chiantla — and in the adjacent highlands of Chiapas in southern Mexico, near Motozintla, El Porvenir and Chamula. The species is therefore confined not to one country but to one mountain chain crossing the border. Elevation runs from about nineteen hundred to nearly twenty-nine hundred metres.

Forms and variation

No wild subspecies or varieties are recognised. The range of variation set out in the description — six to seventeen leaves, one to eight scapes, rosettes from a little over three to ten centimetres — is considerable, and follows the age and the situation of the plant. Because the species is known from so few localities, that picture rests on a small number of populations; new material could easily widen it.

Where and when to see it

Go in late autumn or early winter: November to January is the flowering season, and outside it the plant is virtually impossible to find on a steep grassy slope. Search the steepest ground — the edge of a ravine, a slipped slope, a bare limestone lip — and specifically not in closed vegetation. The altitude demands preparation: this is terrain above two thousand metres with cold nights. Document every find; the species counts as exceptionally rare and every new record matters.

Conservation status

The species has not been assessed for the global IUCN Red List and is not listed in CITES. What is known is emphatically little: at its rediscovery the species was described as exceptionally rare, known from only a handful of collections in a cross-border mountain region. The highlands of the Cuchumatanes and of Chiapas are under pressure from logging, grazing and conversion to farmland, and the steep, open slopes where this species grows are precisely the ones vulnerable to erosion and to trampling by livestock. The absence of an international category says no more than that nobody has made the assessment. For a species with so thin a file, every new, well-documented find can make the difference between 'virtually unknown' and 'assessable'.

Scientific name

Pinguicula clivorum | Standley & Steyermark, 1944

Described by Paul Carpenter Standley and Julian Steyermark in 1944. The type area lies in the border region of Guatemala and Mexico; the species is rare and was only rediscovered decades after its original description. The species name clivorum is Latin for "of the slopes" and refers to the species' habitat on steep mountainsides.

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