Biology of the Araceae in Ghana
The reproductive ecology of nine aroid species in the rain forests around Kumasi in Ghana was studied. These species included two seasonal geophytes; Amorphophallus johnsonii and Anchomanes difformis, two herbaceous species; Culcasia saxatilis and Culcasia striolata, Four hemi-epiphytic species with terrestrial phases; Cercestis afzelii, Cercestis stigmaticus, Culcasia angolensis and Culcasia parviflora, and one hemi-epiphytic species without a terrestrial phase when mature; Rhaphidophora africana. These aroids are pollinated by beetles and flies. Anchomanes difformis and Culcasia angolensis exhibit floral heating. Trap mechanisms are present in the inflorescences of Amorphophallus johnsonii, both Cercestis species, in Culcasia parviflora and in C.saxatilis. Pollen is psilate or verrucate to bacculate in most species, but echinate in Culcasia angolensis. Ripe infructescences in most species consist of clusters of large orange to red coloured berries, but Rhaphidophora africana develops gravid spadices, with the outer tapetum peeling away to reveal naked seeds in a pulp. The seeds in most of these aroids germinate quickly and produce high percentage germination, but Amorphophallus johnsonii exhibits bimodal germination, with some seeds germinating immediately and others delaying germination until 8 months later. Evidence of berry flesh inhibition was found in Cercestis afzelii. Two main patterns of climbing are displayed by the hemi-epiphytic aroid species, with continuous growth in Culcasia angolensis and Culcasia parviflora and periodic climbing shown by Cercestis afzelii, Cercestis stigmaticus and Rhaphidophora africana. Growth towards dark areas or 'skototropism' is evident in Culcasia angolensis, Culcasia parviflora and to some extent in Cercestis stigmaticus.