AFRICAN

ORCHIDS

Platanthera micrantha (Hochst. ex Seub.) Schltr., Repert. Spec. Nov. Regni Veg. 16: 378 (1920).
Homotypic Names:
Habenaria micrantha Hochst. ex Seub., Fl. Azor.: 25 (1840).
Description:
Narrow-lipped Butterfly-orchid: Tubers broadly fusiform, narrowing to a single, long, fleshy apical root; a further 2–4 roots emerge horizontally from the base of the stem; old and new tubers separated by a substantial stolon 30–50% the length of the tuber. Stem 32 ± 18cm, 3.7 ± 2.4 mm in diameter. Sheathing leaves often 2, occasionally 3, largest 125 ± 73 mm × 54 ± 31 mm, broadly ovate/obovate, spreading and lacking an elongate petiole; bracteoidal leaves 3.3 ± 2.6, usually distributed fairly evenly along stem and grading into basal bracts. Inflorescence 109 ± 80 mm, 60 ± 60 flowers (18 ± 16 fls/cm). Basal bracts 21 ± 27 mm, floral bracts 13 ± 6 mm × 4.9 ± 2.0 mm, lanceolate; marginal cells rounded, 47 ± 16 µm in longitudinal diameter. Flowers pea green to agathia green (RHS 142D–149D in natural light, 144D in artificial flash); median sepal ± horizontal and lateral petals torsioned inwards to arch over gynostemium. Labellum often paler towards spur entrance, entire, 4.6 ± 1.6 × 1.6 ± 0.6 mm, linear-lanceolate, projecting clearly forwards but also curved moderately to strongly forwards, obscuring spur entrance. Spur 7.3 ± 1.9 mm long × 0.8 ± 0.5 mm in diameter at mouth, 0.9 ± 0.3 mm midway along its length, usually strongly down-curved; spur entrance strongly compressed vertically. Ovary 11.9 ± 3.5 mm. Lateral sepals oriented closer to vertical than horizontal, 4.9 ± 1.4 × 2.8 ± 0.9 mm. Lateral petals 3.2 ± 0.9 mm. Gynostemium 1.5 ± 0.5 mm long × 1.5 ± 0.5 mm wide; stigma immediately above spur entrance, a horizontally elongate oblong, at most 1.2 ± 0.4 mm wide; rostellum a subdued, near-horizontal ledge; auricles lateral to, and largely fused with, remainder of gynostemium, small to almost absent, 0.5 ± 0.4 mm. Anther locules linked by a narrow, well-developed connective, locule aperture ± linear, relaxed; paired pollinaria 1.2 ± 0.3 mm, slightly to moderately convergent from viscidium to pollinium apex, viscidia separated by 1.0 ± 0.4 mm, apices of pollinaria by 0.6 ± 0.3 mm; viscidia pendent, angled inwards but not opposed, strongly ellipsoidal and concave, clearly bipartite; caudicle near-linear, strap-like, much shorter than the pale yellow pollinium; pollinium bears few vertical rows of massulae. Fragrance combines Freesia and Citrus.
Habitat:
Largely confined to, and a good indicator of, laurisilva scrub and adjacent rough grassland; 300–900(–1100) m asl.
Distribution:
Azores
References:
Systematic revision of Platanthera in the Azorean archipelago: not one but three species, including arguably Europe’s rarest orchid by Richard M. Bateman,corresponding author Paula J. Rudall,1 and Mónica Moura