Pinguicula apuana — Vorstman's Guide to the Carnivorous Plants

Identification

A flat to slightly ascending rosette of entire, oblong-ovate leaves, yellow-green, greasy to the touch and with margins curled upward. Glabrous scapes rise from the centre, each with one two-lipped flower: a two-lobed upper lip, a three-lobed lower lip with throat markings, and a spur behind. Reliable measurements for plant, corolla and spur could not be traced to a checkable source for this guide and are therefore not given. What is established is that the species is polyploid, with a chromosome number twice that of its neighbour P. mariae — and polyploid plants are generally the sturdier build.

Similar species

The key comparison is with Pinguicula mariae, which grows in the same range and closely resembles it. The two are hard to separate in the field and were described as distinct species in the same paper; the difference is genetically sharp — P. apuana has twice the chromosome number — but subtle to the eye, resting mainly on size and flower proportions. Further north-east, on the crest of the northern Apennines, stands P. christinae. For the field-guide reader the practical rule is: record exactly where you are and photograph flower, leaf and fruit.

The trap and how it works

A flypaper trap of the ordinary butterwort type, but in an extraordinary setting. The leaf carries stalked glands with a sticky droplet and sessile glands that release digestive enzymes once prey is lying on them. The catch consists of midges, gnats and springtails living in the humid air along the wet marble faces. After a catch the leaf margin rolls towards the prey, so the digestive fluid stands in a shallow dish rather than running off the steep wall. On flushed marble and limestone there is virtually no nitrogen to be had from the substrate; the insects are not a supplement here but the main meal.

Habitat and ecology

Wet limestone and marble rock: dripping faces, seepage patches under rock bands, and damp, short-cropped ground on the highest slopes. The Apuan Alps are steep and karstic, which means rainfall vanishes into the mountain at once and re-emerges far lower down; this plant's sites lie precisely at those emergence points. Shading by advancing scrub and the drying of a seepage patch are the two ways such a site disappears. The species tolerates neither.

Distribution and elevation

Only the Apuan Alps in Tuscany, Italy, and within them a limited number of wet faces and slopes. The entire world range covers a mountain chain barely fifty kilometres long. That the Apuan Alps hold two butterworts of their own alongside a suite of other endemics is no accident: the massif is old, steep, calcareous and cut off from the Apennine crest by the sea and by broad valleys, and such mountains keep species that have gone elsewhere.

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 2 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

No wild varieties are recognised. The taxonomy of the Apuan pair is in motion, though: molecular work on the Italian butterworts has shown that P. apuana and P. mariae sit at different ploidy levels and need not be each other's closest relatives, which leaves the exact boundary unsettled. Within the species, variation follows the site: on the wettest faces the plants grow more generously and flower more freely than in a merely damp crevice.

Where and when to see it

May and June, while the winter's water is still working through the karst. Look for the wet streaks on the faces — in the Apuan Alps these are visible from a distance as dark bands across pale rock — and follow them to the foot. The rosettes often sit above eye level in a crevice. This is a range with working marble quarries and much loose stone; keep to the paths, do not climb the faces, and use binoculars. Record the locality precisely: for these recently described species a good observation is worth more than a collected plant.

Conservation status

The species has not been assessed for the global Red List; there is no international category and CITES does not apply. What is known: an endemic of a single range, with a small number of sites all dependent on a steady water supply. The greatest and, in this range, very concrete risk is marble quarrying, which reshapes whole mountain flanks and can sever the water paths through the karst; alongside that come drying in longer dry summers, the rank growth of short-cropped slopes, and removal of plants by collectors. An assessment would probably land in a threat category; that it is missing is a gap.

Scientific name

Pinguicula apuana | Casper & Ansaldi, 2009

Described by Siegfried Jost Casper and Alessandro Ansaldi in 2009, in a paper on the occurrence of the genus Pinguicula in the Apuan Alps (Tuscany, Italy). The type area lies in the Apuan Alps in Tuscany, Italy. The species name apuana refers directly to the Apuan Alps, where the species is endemic.

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