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Pinguicula crenatiloba
This is the smallest butterwort of the American mainland and probably of the whole genus: a rosette barely one to two centimetres across, with leaves five or six millimetres long, lying like a green dot in the moss of a wet mountain forest. Pinguicula crenatiloba was described as long ago as 1844, but it is still rarely seen — not because it is rare, but because hardly anyone looks at a small enough scale.
Identification
An extremely small, flat rosette, usually one to two centimetres across, of a handful of pale green leaves reaching at most five or six millimetres. The leaf margin is finely scalloped — hence the name — and the upper surface carries the usual glittering glandular droplets, though at this size the glandular coating is barely recognisable as such with the naked eye. The scapes are thin and short and carry a single minute flower, in which the lower lip appears three-lobed and the short spur is strongly bent forwards. Flower colour is reported in the literature as pale, white to light violet; because we could not find a testable colour or measurement statement in a flora or monograph, the colour field on the fact card has been left empty. The plant is self-pollinating and almost always sets seed.
Similar species
Nothing to confuse it with once you register the size: no other butterwort on the Central American mainland stays this small. Substantial species such as Pinguicula moranensis, P. mesophytica and P. hemiepiphytica share the region, and all have rosettes ten to thirty times larger. The real confusion is of a different order: a five-millimetre rosette among moss is taken for a liverwort gemmaling or a young Utricularia rather than for an adult carnivorous plant. Search at the right scale and it is recognisable by the scalloped leaf margin and by the glitter on the blade, which the mosses lack.
The trap and how it works
The trap is the same active flypaper as in the large species, only in miniature. Stalked glands supply a sticky droplet, sessile glands release digestive enzymes on contact with prey, and the leaf surface bends slightly upwards around a catch. At this size the menu is proportional: springtails, minute flies and mites living among the moss. That is exactly what keeps the plant alive, because on the sodden, leached forest soil where it grows nitrogen is scarce, and the smallest animals of the litter layer are the most accessible protein available. A one-millimetre catch is a full meal for a five-millimetre leaf.
Habitat and ecology
Wet open spots in montane forest: on soil among mosses in permanently damp woodland, on mossy banks and earth faces, and along the edges of forest paths and rills. The species needs ground that never dries out but is not submerged either, and enough light not to be shaded out — bare, wet mineral soil under a thin coat of moss is the ideal. Being so small, it can use sites too cramped for a larger rosette: the top of a clod, the rim of a hoofprint, a fresh slip beside a trail. That makes it a pioneer, appearing quickly after disturbance and disappearing again as taller plants close in.
Distribution and elevation
From southern Mexico through Central America: Kew gives the native range as Mexico to Central America, with records from Guatemala, El Salvador, Honduras, Costa Rica and Panama. In Mexico the species is known among other places from Oaxaca, on the trail from Totontepec to Ocotepec, and from the surroundings of Tejupilco. Our account differs here from the guide's own species list, which gives Mexico only: the range is in fact far wider and covers much of the Central American cordillera. The species is therefore not endemic. Given its size it is almost certainly under-recorded, and there will be more sites than the map shows.
- Recorded (quarter-degree cells)
Forms and variation
No wild varieties are recognised. In a self-pollinating plant with a large but strongly fragmented range one would expect many local forms, and they may well exist; they have simply never been investigated systematically, because little material has been collected and herbarium specimens of a five-millimetre plant rarely preserve the characters you need. The observed variation concerns mainly size and the number of flowers per plant, and that seems to track the wetness of the site rather than ancestry. No natural hybrids are known.
Where and when to see it
This is a species for anyone willing to kneel. Search during the rains on wet, half-shaded earth banks and moss cushions along forest trails in montane forest between roughly one and two thousand metres, and work through half a square metre at a time. A hand lens or a macro lens is essential: with the naked eye you see at best a paler speck in the moss. Wet weather is in your favour, because the droplets are then full and the little leaf glitters. Check fresh slips and path edges as well — pioneer ground yields more than closed forest.
Conservation status
The species has not been assessed for the global IUCN Red List and is not listed in CITES. At first sight what is known is reassuring: the range covers a considerable part of Central America across five or six countries, and the species is a pioneer that profits from small-scale disturbance. Against that, it depends entirely on permanently humid montane forest, and that is precisely the vegetation type declining fastest in Central America through deforestation, coffee growing and desiccation. Because the plant is so small and so poorly collected, data on population size and trend are almost wholly lacking. The absence of an assessment is here above all a knowledge problem.
Scientific name
Pinguicula crenatiloba | de Candolle, 1844
Described by Augustin Pyramus de Candolle, based on material by Mociño and Sessé. The type area lies on the trail from Totontepec (Mixe) to Ocotepec, in the Mexican state of Oaxaca. The species name crenatiloba is Latin for "with scalloped lobes" and refers to the scalloped lips of the small flower.
World Checklist of Vascular Plants (WCVP), via Plants of the World Online (POWO), Royal Botanic Gardens, Kew.