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Angraecum borbonicum Bosser, Bull. Mus. Natl. Hist. Nat., B, Adansonia 10: 20 (1988).
Description:
Plants epiphytic, erect or pendulous with age; stem single, (15-)20-50 mm long, covered with old leaf sheaths; internodes 1.1-2.1 mm. Roots many, basal, 2-3 mm diameter, smooth, silvery-grey. Leaves 4-8, rigid, (20)40-120 x 7-15 mm, linear-oblong, coriaceous, dark green, slightly V-shaped, sometimes recurved at the apex, unevenly bilobed. Inflorescences 1 to 2, single-flowered. Peduncle 5-8 mm long; covered by 2 to 3 imbricate sheaths; sheaths 3-10 mm, ovate, concave, obtuse, sometimes tip keeled, smooth, covered with small glands. Floral bracts (2-3-)6-7 mm long, ovate. Flower resupinate, 25-50 mm diameter, white, fleshy, opening only rarely, odourless, nectariferous with only few drops of nectar present. Sepals narrowly-ovate, 20-23 x 5-6 mm, acuminate, 7-veined; median sepal slightly wider than the laterals, 9-veined, acute. Petals similar in shape to sepals, 22-26 x 3-4 mm, 5- veined. Labellum 20-23 x 15-20 mm, largely ovate, acuminate. Spur (55-)65-70 mm long, filiform, pendulous, more or less curved, rarely straight. Column 1.5-2.0 mm high, fleshy; auricles truncate. Anther cap 1.5 mm diameter, keel gibbous. Rostellum abnormally developed. Pollinia 1.2 mm long, ovoid, in direct contact with stigma (autogamy). Ovary (including peduncle) 30-40 mm, narrowed at the base, triangulate. Capsule triquetrous, erect, 40-50 x 15-20 mm, long lasting; peduncle 10-15 mm long; thick.
Habitat:
Mid-elevation and mountainous moist forest, especially on ridges between 400-1500 m elevation. Often epiphytic on Ericaceae [Erica Linnaeus (1753: 352) and Agarista D.Don ex Don (1834: 837-838) in particular], sometimes near to the ground in Acacia heterophylla (Willdenow 1806: 1054-1055) forests (type ‘avoune’ - https://inpn.mnhn.fr/habitat/cd_hab/18671), where it forms dense colonies. Frequency of populations within its suitable habitat is quite high. It is an autogamous species with high fruit set.
Phenology:
Flowering in December and January. Flowers usually open for three days.
Notes:
This species is often found in fruit because the flowers appear to be self-pollinating. The 3-angled, erect capsules are characteristic. It has been known, in the past, as Angraecum triquetrum but that name has been transferred to Jumellea by several authors (Bosser 1988).
Distribution:
Réunion.
References:
Revision of Angraecum sect. Perrierangraecum (Orchidaceae; Epidendroideae; Vandeae) for the Mascarenes, with a description of a new endemic species for Mauritius; POWO (2022). "Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://www.plantsoftheworldonline.org/ Retrieved 21 November 2022."
Images:
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Habitat/In situ	Habitat/In situ	Habitat/In situ
Photograph P. Bernet ©Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission.	Photograph P. Bernet ©Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission.	Photograph P. Bernet ©Swiss Orchid Foundation at the Herbarium Jany Renz Image used with kind permission.