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Pinguicula longifolia
The long-leaved butterwort of the Pyrenees, a plant of dripping limestone walls in the shaded, cool gorges of the high valleys. Pinguicula longifolia changes shape through the season: a compact spring rosette becomes in summer a crown of long lanceolate leaves hanging up to seventeen centimetres out of the rock.
Identification
A perennial rosette plant with a minimal root system, forming new rosettes on stolons and overwintering as a winter bud. The spring leaves are obovate to elliptic and two and a half to six and a half centimetres long; the summer leaves become much longer and narrower, seven to seventeen centimetres, lanceolate, hanging slack over the wall. All leaves are sticky and glandular. The flower is violet, with a short funnel-shaped tube and a corolla eighteen to twenty-seven millimetres across; the spur is conspicuously long, nine to sixteen millimetres, cylindrical-subulate and straight or slightly curved. Flowering is May to July.
Similar species
Two closely related species grow on Iberian limestone. Pinguicula vallisneriifolia, from the Andalusian sierras, has far longer, strap-shaped summer leaves — twenty centimetres and more — and a larger flower of twenty-five to thirty-five millimetres; the ranges are also far apart. P. mundi, from the Albacete–Jaén border, has shorter summer leaves of six to eleven centimetres and a smaller flower whose upper lip is darker than the lower. In the Pyrenees themselves the main risk is P. grandiflora, but that has short broad leaves and a much larger, almost flat flower.
The trap and how it works
A flypaper trap built for a vertical, permanently wet limestone wall. The long narrow summer leaf gives the plant much sticky surface without needing anything to rest on; it hangs free of the rock, exactly in the airflow along which small insects move past the face. The stalked glands carry the droplet, the sessile glands beneath release digestive enzymes as soon as prey is lying there, and the margin rolls over the catch so that the fluid does not run straight down the leaf. On tufa with water flowing across it, that is the only way to keep anything of a catch.
Habitat and ecology
Wet limestone rock and travertine walls with spring water seeping over them, usually shaded, between nine hundred and two thousand metres (R1, R2). The plant sits in crevices and on moss cushions directly on the rock, without real soil. The climate is cool and damp; in winter there is snow and the walls are often partly frozen. The site is base-rich but poor in nitrogen and phosphorus — the running water carries off everything loose. There is hardly any competition from taller plants, because almost nothing else gets a grip on such a wall.
Distribution and elevation
Endemic to the Pyrenees in the strict sense, centred on the central chain in the Spanish province of Huesca and on the French side of it. Some authors also place two isolated subspecies in this species: one in the French Causses and one in the southwestern Alps. Under that broader concept the distribution is further broken up across three widely separated limestone regions. Our own species list names the Pyrenees, which matches the species in the strict sense. Elevation runs from nine hundred to two thousand metres.
- Recorded (quarter-degree cells)
Forms and variation
The main variation in form is seasonal and applies to all plants: the switch from short spring leaves to long summer leaves, which gives the same plant two quite different appearances in May and in August. Beyond that there are the geographical subspecies mentioned: subsp. caussensis from the French Causses and subsp. reichenbachiana from the Maritime Alps are kept within this species by some authors and treated as independent by others. Natural hybrids with P. grandiflora have been described in the Pyrenees; they are intermediate in build and belong in this guide with the parents.
Where and when to see it
Search in June in the gorges and narrow valleys of the central Pyrenees, on the shaded side. The best walls are wet and mossy and overhang, with water running across them all day; the plants sit there at eye level and above. The violet flowers with their long spur can be seen from ten metres, long before the rosette. Stay on the path and do not climb the wall — the moss cushions the plant roots in come away at once underfoot, and the populations on any one wall are not large.
Conservation status
The species is assessed as Least Concern on the global IUCN Red List, with a population trend regarded as stable, and is not in CITES. On the Spanish side it also enjoys legal protection. That does not alter the fact that this is an endemic plant with a limited range, entirely dependent on walls with permanently flowing spring water. The risks follow from that: declining spring flow in longer droughts, capping of springs for drinking water and stock troughs, and local damage from climbing and from treading on mossy walls. For a species occupying only a handful of square metres per wall, such local interventions weigh more heavily than the global category suggests.
Scientific name
Pinguicula longifolia | de Candolle, 1805
Described by Louis Ramond de Carbonnières, published by Augustin Pyramus de Candolle in 1805. The species is endemic to the Central Pyrenees, on both sides of the French-Spanish border. The name "longifolia" is Latin for "long-leaved": in summer the leaves can grow up to 14 cm long, unusually long for the genus.
World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.