Pinguicula grandiflora

Big flowers in three colors

ICPS singles out this species for its large, showy spring flowers ^[9]. The usual form has dark flowers, but there are well-marked color forms. Jurg Steiger described two pale ones in continental Europe ^[11]:

• f. pallida: pale blue with a dark blue spot at the base of the central lower lobe, common in Jura valleys north of Geneva. It always grows among normal dark-flowered plants, and neither its calyx, stem, seed capsule nor winter bud shows any red or purple pigment.
• subsp. rosea: pink-white with reddish stripes in the throat, slightly smaller flowers, a shorter and slimmer purple spur, and a purple calyx. It grows in the mountains near Grenoble, and Steiger considered it geographically and genetically isolated, with neither the dark form nor f. pallida present there.

Later fieldwork qualifies that: Roccia found subsp. grandiflora in the higher part of an Isère bog where subsp. rosea also grows ^[2]. A white-flowered form, f. chionopetra, comes from Ireland and the Pyrenees ^[2]. As early as 1956, D. A. Webb of the University of Dublin sent Steiger an almost white plant from the Burren in County Clare ^[11]. Steiger found the same chromosome number in all forms, 2n = 32 ^[11]. In the phylogeny-based classification it sits in section Pinguicula with P. vulgaris and the other winter-bud species ^[12].

Not just a bigger P. vulgaris

The two species grow together in places, and hybrids between them were long mistaken for P. grandiflora ^[2]. Two less obvious differences separate the parents. P. grandiflora has 2n = 32 chromosomes, half the 64 of P. vulgaris, which Steiger read as a sign that P. grandiflora is the older species ^[11]. It also multiplies freely: its winter buds are ringed with tiny gemmae, while P. vulgaris usually makes none, or one a year at most ^{[9, 13]}. In flower, Roccia points to the well-defined, rectangular spot on the palate of subsp. grandiflora; in the hybrids the spot is rounded ^[2].

The leaves react to prey. When an insect stimulates the surface, the leaf forms a shallow depression around it, a movement engineers have studied as a model for self-shaping materials ^[14]. A 2025 study of photosynthesis in butterworts found that several Mexican species switch to a water-saving CAM pathway under drought, but P. grandiflora showed no CAM induction ^[3].

Ireland and the Pyrenees, but not Britain

The native range has a gap. Roccia lists northern Spain, the French Pyrenees, Massif Central, Jura and Alps, two Swiss localities and Ireland, plus a recent find in northern Italy, and notes that British plants were introduced ^[2]. WCVP also treats the plants in Great Britain, Germany and Czechia-Slovakia as introduced ^[1].

This “Lusitanian” pattern, which it shares with the saxifrage Saxifraga spathularis, led botanists to ask whether P. grandiflora survived the last ice age in Ireland. Beatty and colleagues combined climate modeling with DNA from across the range. They concluded it sheltered in a single large refuge across northern Spain and southern France and reached southwest Ireland after the ice retreated. Irish populations showed extremely reduced genetic diversity compared with the mainland ^[5]. Despite that, the species is not considered threatened in Ireland ^[4].

Hybrids with P. vulgaris

The natural hybrid P. ×scullyi was named by Druce in 1922 from Irish material, and has also been recorded in Andorra and the Alps ^[2]. In 2013 Roccia described a second, sterile hybrid in the Grésivaudan valley near Grenoble, between subsp. rosea and P. vulgaris. It grows in shady seepages where neither parent does well, and its lavender to blue flowers are intermediate in color ^[2]. Under the botanical code the new hybrid had to become a nothosubspecies of the older name: P. ×scullyi nothosubsp. gresivaudanica ^[15]. These crosses fit Fleischmann’s observation that species within one section hybridize readily ^[12].

Growing it

Grow it like other cold temperate butterworts in the genus overview: cool and bright in summer, cold in winter. In a mild, wet climate it can live outdoors all year; ICPS lists it among the plants that did well in a 50:50 peat and sand bog garden in North Vancouver ^[10]. See bog gardens. Mrkvicka suggested keeping European winter-bud species outdoors where possible and not repotting them at all, to protect the roots ^[6]. Rice, growing in a refrigerator-assisted cycle, repotted about every second year at the start of dormancy ^[8]. The dormancy guide compares winter methods.

Its habitat is often summarized as moist and shady ^[3], but at one heavily shaded site Roccia found only a few pale plants of the pink form, which were disappearing for lack of light, while both parents of the hybrid grew in sunnier spots nearby ^[2]. Mrkvicka’s “slightly shaded” summer position is a reasonable middle course ^[6]; see light.

Propagation

The easiest offsets are the gemmae, tiny buds that form around the base of the winter bud; ICPS shows a hibernaculum ringed with them ^[9]. Rice describes detaching such buds, which can be less than 1 mm long, before dormancy and marking them so they are not lost in the pot ^[8].

Seed needs 8 to 12 weeks at -10 to 5°C. ICPS shows seedlings that were stratified outdoors over winter in a metal box, germinated under lights indoors on a natural day length, and then returned outdoors without protection ^[9]. See cold stratification and sowing seeds.