Bulbophyllum maximum

Bulbophyllum maximum (Lindl.) Rchb.f. in W.G.Walpers, Ann. Bot. Syst. 6: 259 (1861).

Section: Megaclinium

Distribution: Across tropical Africa

Epiphytic in open woodland and riverine forest, up to 5000ft. Stout woody rhizome with angled psuedobulbs, two leathery leaves up to 8" long. Inflorescence up to 20" long; with flattened rhachis (blade-like)up to 7" long. Up to 60 x pale yellow or yellowish-green 3mm flowers,sometimes more, along either side of the rhachis.
Looking at the image you can see the development of the buds and the extending rhachis.
bernabu