is a monoecious genus
of flowering plant
in the palm
family found in western Africa
. The genus is the lone member of the Oncocalaminae
; once placed with the vegetatively similar Eremospatha
in the Ancistrophyllinae
, it is now isolated based on their unusual flowers and arrangement. Such a placement argues for a long and complex evolutionary process in the Calamoideae
with heavy extinction
rates. The Greek
genus name combines "horn" and "capsule".
The trunks are small, very spiny, and high climbing, becoming bare with age. All species form dense clusters with undivided or bifid juvenile leaves
which become pinnate
in maturity, with leaf sheath spines, leaflet cirri, and spiny petioles, all adapted for climbing. The leaflets are few to many, with one, two, or more folds, entire, acute, linear or sigmoid, and regularly arranged along the rachis.
As hapaxanths, the inflorescence emerges at the top of the stem, amongst reduced leaves, with male and female flowers, on a once-branched spike. The flowers are arranged in clusters of up to 11, with one or three pistillate and two to four staminate flowers at the center of the cluster. The fruit is spherical and covered in vertical rows of yellow to brown scales with one seed.
Distribution and habitat
Strictly low land rain forest
inhabitants, they are found in equatorial