Pinguicula alpina — Vorstman's Guide to the Carnivorous Plants

Pinguicula alpina — the trap in close-up — **The trap in close-up** · Photo: Filip Dominec — Public domain · Wikimedia Commons

Pinguicula alpina — the flower — **The flower** · Photo: Philipp Weigell — CC BY 3.0 · Wikimedia Commons

Pinguicula alpina — the habitat — **The habitat** · Photo: Nicolas Weghaupt — CC0 · Wikimedia Commons

Identification

A flat rosette of five to eight ovate, entire leaves, yellow-green to almost butter-yellow, with the margins of older leaves rolled upward. The upper surface feels greasy — which is where the scientific genus name comes from — and glistens with glandular droplets in raking light. One to several glabrous scapes rise from the centre; in flower the plant stands 5 to 15 cm tall. The flower is white and two-lipped, with a two-lobed upper lip and a three-lobed lower lip bearing one or two bright yellow blotches pointing into the throat. Behind it sits a short, straight spur 2 to 4 mm long, yellow to brownish green. Flowering runs from May to July, and higher in the mountains into August. After flowering the plant withdraws into a winter bud, often surrounded by small brood buds.

Similar species

The species it is most often mistaken for is Pinguicula vulgaris, which lives in the same mountains and sometimes in the same fen. That has a violet to blue-purple flower with a long, pointed spur 4 to 7 mm long, and generally greener, less yellow leaves; the flower colour is unmistakable, and out of flower the yellowish cast of P. alpina is the best character. A few local species in southern Europe, such as P. poldinii and P. balcanica, also have whitish flowers, but their ranges barely overlap. In limestone country a rosette without flowers is almost certainly this species if it is yellow-green with inrolled leaf margins.

The trap and how it works

An active flypaper trap, but with a movement you only notice after hours. The leaf surface carries two kinds of gland: stalked glands producing a sticky droplet, and sessile glands that release digestive enzymes only once prey is lying on them. A small insect landing on the leaf sticks fast; struggling brings it into contact with more glands, and at the same time the plant begins a slow growth response in which the leaf margin rolls over towards the prey, so that the digestive fluid pools in a shallow dish instead of running off. Afterwards the leaf flattens again. The catch is mostly midges, gnats and other small flying insects that swarm in spring habitats. How indiscriminate the plant is shows on an old leaf: it lies covered in the black husks of what has been eaten.

Habitat and ecology

Irrigated, base-rich and cold, in three words. The plant grows on wet rocks and tufa walls over which spring water seeps (R1, R2), in calcareous fens and small sedge mires (W2), and in damp, closely grazed mountain pasture. It tolerates no drought, no acid substrate and no shading by tall vegetation; it avoids competition by growing where almost nothing else can stand — on a bare, permanently wet limestone slope where the water washes the nutrients away. That poverty is exactly what makes carnivory pay. Towards the north of the range the habitat descends to sea level and the tundra takes over the role of the high mountains.

Distribution and elevation

A broad northern and montane distribution: from Iceland and Scandinavia across the Alps, the Carpathians and the Pyrenees to the Balkans, and eastwards through Siberia to the Himalaya and western China. The species is therefore anything but endemic. Its altitudinal span is correspondingly wide: in northern Siberia and Scandinavia it reaches the coast, in the Alps it occupies roughly the montane to alpine belts, and in the Himalaya it has been recorded above four thousand metres. It does not occur in the Low Countries; the nearest populations are in the Jura and the Alps.

Recorded (quarter-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 285 quarter-degree squares in which the species has actually been recorded, from GBIF and only from records accurate to within five kilometres. They show where it has been seen, not where it occurs: an empty square means nothing. For threatened species this layer never goes finer than a whole degree, deliberately.

Forms and variation

For so large a range the species is strikingly uniform, and no wild varieties are recognised. What varies is size and intensity of colour: plants on a lean, sunny limestone face stay small and markedly yellow, while plants in a sheltered fen grow larger and greener. The number of yellow blotches on the lower lip shifts between one and two, occasionally three, and is not a dependable character. Natural hybrids with Pinguicula vulgaris have been described where the two grow together; those plants have a pale lilac flower with a yellow throat mark and a spur of intermediate length, and they are almost always sterile. In this guide they belong with the parents.

Where and when to see it

June is the best moment in the Alps, at whatever altitude the snow has just left; climbing higher later in the season lets you follow the melt line and the flowering with it, into August. Search along water rather than out in the meadow: the edges of spring-fed rills, wet tufa slopes, the dripping foot of a cliff, and small sedge fens on lime. Get low — from standing height the rosette reads as a clump of moss, and without flowers it is routinely walked past. A low morning sun lights up the glandular coating and betrays whole colonies at once.

Conservation status

The species has not been assessed for the global IUCN Red List, so it carries no international category, and it is not listed in CITES either. What is known gives no cause for concern at the level of the species: the range covers much of northern Eurasia and the high-mountain populations are large. At the edges of the range the picture differs. In several central and southern European countries it appears on national red lists, and the causes named are always the same: the draining and fertilising of calcareous fens, the capping of springs, and the rank growth of closely grazed mountain pastures once the livestock goes. The absence of a global assessment is therefore a gap in the file rather than reassurance about what is happening locally.

Scientific name

Pinguicula alpina | Linnaeus, 1753

Described by Carl Linnaeus in 1753, in “Species Plantarum”. The species occurs naturally across much of northern Eurasia, from Iceland to the Himalayas, from sea level in north-western Siberia up to 4100 metres elevation; the densest populations lie in the Alps and northern Scandinavia. The species name alpina is Latin for "of the Alps, alpine" and refers to the species' main habitat in high mountain regions.

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