Aerangis gravenreuthii (Kraenzl.) Schltr., Beih. Bot. Centralbl. 36(2): 117 (1918).
Homotypic Synonyms:
Aeranthes gravenreuthii Kraenzl., Bot. Jahrb. Syst. 17: 62 (1893).
Mystacidium gravenreuthii (Kraenzl.) Rolfe in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 7: 171 (1897).
Heterotypic Synonyms:
Angraecum ellisii var. occidentale Kraenzl., Bot. Jahrb. Syst. 17: 59 (1893).
Angraecum gravenreutii Kraenzl., Bot. Jahrb. Syst. 17: 62 (1893).
Angraecum stella Schltr., Bot. Jahrb. Syst. 38: 163 (1906).
Description:
Stem woody, up to 5 mm diam., 7 cm long, bearing several leaves 5-10 mm apart in the apical part and numerous greyish, flexuous roots up to 3 mm in diameter below. Leaves distichous, oblanceolate, gradually narrowed towards the sheathing base, apex unequally bilobed, the lobes acute, 3-18 mm long, dark green, reticulate venation conspicuous in the dry state, margins entire, up to 15 x 1-5-3 cm. Inflorescences pendent axillary racemes, 10-20 cm long, bearing 2-5 flowers; peduncle terete, slender, to 8 cm long, 1-2 cm in diameter and bearing several loose sheaths; rhachis ? straight or curved; bracts ovate to 5 mm long. Flowers erect, white, sometimes with orange pink flush, and pink spur, 1-2-2 cm apart; pedicel with ovary 3-5 cm long. Dorsal sepal erect or arching forward over the column, narrowly ovate in the lower half becoming long acuminate, 20-32 x 5 mm; lateral sepals spreading or reflexed, oblong-ovate below, acuminate above, 20-35 x 5-5-5 mm. Petals reflexed, obovate below, acuminate above, 15-25 x 4 mm. Lip oblong-ovate below, long-acuminate above, 17-25 x 5 mm; spur curving forwards, somewhat inflated in the apical half (Tanzania specimens) but narrow at the apex, 4-6(-8) cm long. Column short, 5 mm long, inflated above and the stigmatic surface elongated; anther cap shortly beaked; pollinia oblong-globose; stipes short and broad; viscidium almost square, the edges clasping the blunt-ended rostellum.
Habitat:
Forests in deep shade, 1500-2200 m.
Cultivation:
As given for the genus.
Notes:
This species has been known from a few localities in Cameroun for a long time and there have been recent gatherings from Fernando Po. When Schlechter described it (as Angraecum stella) he pointed out that it was somewhat similar to Aerangis kirkii Rolfe. In the short, few-flowered inflorescences these two species are very similar, but in Tanzania, where both species have now been recorded in the Uluguru mountains, although at widely spaced altitudes, they are easily distinguished by their different leaves and by small differences in the flowers. All the tepals are much less acuminate in Aerangis kirkii than in Aerangis gravenreuthii. The specimens from Tanzania have shorter spurs that are somewhat inflated in the apical half, but this is the only difference that can be detected between them and plants from Cameroun. The specimens from Fernando Po have much narrower leaves than the type, but the flowers are unmistakably similar.
Distribution:
Bioko, Cameroon, Tanzania (Uluguru Mts.)
References:
Flora of Tropical East Africa - Orchidaceae v3 (1989), Bind 136,560; Stewart, J. (1979). A Revision of the African Species of Aerangis (Orchidaceae) Kew Bulletin, Vol. 34, No. 2 (1979), pp. 239-319;WCSP (2017). 'World Checklist of Selected Plant Families. 19.01-2017; http://apps.kew.org/wcsp/
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