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Aerangis arachnopus (Rchb.f.) Schltr., Beih. Bot. Centralbl. 36(2): 113 (1918).
Homotypic Synonyms:
Angraecum arachnopus Rchb.f., Bonplandia (Hannover) 2: 93 (1854).
Angorchis arachnopus (Rchb.f.) Kuntze, Revis. Gen. Pl. 2: 651 (1891).
Heterotypic Synonyms:
Angraecum batesii Rolfe in D.Oliver & auct. suc. (eds.), Fl. Trop. Afr. 7: 139 (1897).
Angraecum biloboides De Wild., Not. Pl. Util. Congo 1: 144 (1903).
Rhaphidorhynchus batesii (Rolfe) Finet, Bull. Soc. Bot. France 54(9): 39 (1907).
Aerangis batesii (Rolfe) Schltr., Bot. Jahrb. Syst. 53: 599 (1915).
Aerangis biloboides (De Wild.) Schltr., Beih. Bot. Centralbl. 36(2): 114 (1918).
Description:
A short, monopodial epiphyte with fine roots that are long, gray, and up to 0.1 in. (0.3 cm) in diameter. Pseudobulb/stem short, with leaves forming a fanlike growth. Leaves four to six oblanceolate or obovate leaves in with unequally and obtusely bilobed tips are distichously arranged and held in spreading positions along the stem. The leaves are rather light green and may sometimes be dotted with black. Inflorescence up to 24 in. (60 cm) long. The pendent inflorescence is very slender, with flowers set 1.2-2.0 in. (3-5 cm) apart on a rather zigzag rachis. Each blossom is carried on a long, slender pedicellate ovary that is salmon-pink and up to 1.6 in. (4 cm) long. Floral bracts are black and up to 0.1 in. (0.3 cm) long. Flowers 3-8 per inflorescence. The flowers are white but the floral segments are strongly tinged with pink toward their tips. The sepals, petals, and lip are all narrowly lanceolate and taper to sharply pointed tips, The dorsal sepal is up to 0.9 in. (2.2 cm) long by 0.2 in. (0.4 cm) wide and has margins that are slightly recurved. The lateral sepals are similar to the dorsal sepal but are slightly curved and reflexed. The petals are up to 0.9 in. (2.2 cm) long by 0.1 in. (0.3 cm) wide and are somewhat reflexed. The lip is 1 in. (2.5 cm) long by 0.2 in. (0.4 cm) wide toward the base. It is deflexed, has margins that curve toward the rear, and has a spur at the base that is 2.4-2.8 in. (6-7 cm) long that is held parallel to the ovary at the base but then curves abruptly downward through about a 90 angle and narrows from 0.08 in. (0.2 cm) to 0.04 in. (0.1 cm) in diameter at the bend. The slender column is up to 0.3 in. (0.7 cm) long and is pink at the base.
Habitat:
This orchid has been collected in Cameroon, Congo, Gabon, Zaire, and possibly Ghana. The type specimen was said to come from Ghana, but between then and the present, the species has not been found there again. Plants are found in evergreen forest below 3300 ft. (1000 m), and I. and E. la Croix (1997) reported having seen them growing profusely on old citrus trees in an abandoned garden at 1300 ft. (400 m).
Notes:
With its long slender inflorescences and widely spaced flowers, which are rather small and narrow in all their parts, it is not likely to be confused with any other species. It appears to be restricted to very humid forests around the Gulf of Guinea. It is very doubtfully recorded from Ghana, as the specimen from which the type was prepared is said to have been 'introduced through' Consul Schiller in 1854, and the species has not been recorded from Ghana since then.
Cultivation:
Read more of Cultivation of Aerangis arachnopus (Rchb.f.) Schltr.
Distribution:
WC. Trop. Africa
References:
Beih. Bot. Centralbl. II. 113 (1918) Hillerman, F. and A. Holst. 1986. An introduction to the cultivated Angraecoid orchids of Madagascar. Timber Press, Portland, Ore.African orchids in the wild and in cultivation. Timber Press, Portland, OR. 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. 08.01-2017; http://apps.kew.org/wcsp/
Images:
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Photograph© Ehoarn Bidault/ Missouri Botanical Garden. Image used with kind permission.	Photograph© Ehoarn Bidault/ Missouri Botanical Garden. Image used with kind permission.	Photograph© Ehoarn Bidault/ Missouri Botanical Garden. Image used with kind permission.	Photograph© Ehoarn Bidault/ Missouri Botanical Garden. Image used with kind permission.	Photograph© Ehoarn Bidault/ Missouri Botanical Garden. Image used with kind permission.	Photograph Gilles Grunenwald. Image used with kind permission.	Photograph Gilles Grunenwald. Image used with kind permission.	Photograph Gilles Grunenwald. Image used with kind permission.