Irlbachia breviflora

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Irlbachia breviflora

Description

Herb, 40-80(-150) cm high, sparsely branched. Stems and branches up to 0.5 cm in diam., terete, with 2 narrow wings on each side of stem; internodes 0.8-12 cm long. Leaves sessile to shortly petiolate, arranged close to base or spread out along stem; petiole 0-1.2 cm long; blade membranaceous to coriaceous, narrowly elliptic, lanceolate, to broadly elliptic, 1.1-8 x 0.4-2.6 cm, margin flat, apex acute, base rounded to slightly attenuate, midvein raised below, with 1 pair (rarely 2) of basal arcuate secondary veins. Inflorescence 3-70-flowered, long-stalked; bracts awl-shaped, ca. 1-2 x 0.5-1 mm; pedicel 1-8(-11) mm long. Flowers erect, horizontal or nodding; calyx green, 3-5 x 3-4 mm, lobes elliptic, 2 x 2 mm, margin hyaline, apex obtuse; corolla white, blue, to purple, throat and midrib inside white-striped, broadly funnel-shaped, 10-19 mm long, 4-8 mm wide at mouth, lobes elliptic, 3-6 x 5-6 mm, apex acuminate; stamens exserted from corolla mouth, filaments 6-11 mm long, bent, anthers white, linear, 2-3 mm long, recurved after anthesis; pollen exine reticulate with groups of spines in polar areas; pistil ca. 10 mm long, ovary ca. 3 x 2 mm, style 4-12 mm long, stigma lobes narrowly oblong, 1-2 x 1-2 mm. Fruit erect, horizontal or slightly nodding, brown, ovoid-ellipsoid, 6-9 x 3-4 mm; seeds brown, ca. 1 mm in diam.

Distribution

Guianas: present Guyana, Republic of: present Pakaraima Mts: present S Venezuela, tepui summits and slopes: present
S Venezuela, tepui summits and slopes, and adjacent Guyana (Pakaraima Mts.); 67 collections studied, of which 12 from the Guianas (GU: 12).

Phenology

Flowering and fruiting .

Notes

This species shows large plasticity, with plants only 5 cm high in moss-covered habitats to ca. 80 cm high in open sandy areas. Irlbachia breviflora is very similar to the lowland species I. nemorosa (Willd. ex Roem. & Schult.) Merrill, which is found in S Venezuela and N Brazil. Both species show extensive variability and some researchers have treated them as conspecific. The main differing characteristic is the longer peduncle of I. breviflora, giving it a long-stalked inflorescence, and a tendency to have the leaves aggregated closer to the base. Seeds of I. breviflora also appear to have only concave cells, whereas plants from the lowlands have seeds with both dome-like and concave cells, but this needs to be confirmed with additional studies.
This species has been known as I. cardonae (Gleason) Maguire until now. Studies of the type material of Lisianthus breviflorus Benth. identified these as the same species. Since Bentham’s name (1840) has nomenclatoral priority over Gleason’s name (1939), the name of the species had to be changed.