''Oncocalamus'' is a monoecious

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s in the

palm Palm most commonly refers to: * Palm of the hand, the central region of the front of the hand * Palm plants, of family Arecaceae **List of Arecaceae genera * Several other plants known as "palm" Palm or Palms may also refer to: Music * Palm (ba ...

family found in western

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. The genus is the lone member of the Oncocalaminae; once placed with the vegetatively similar ''

Eremospatha ''Eremospatha'' is a genus of climbing flowering plants in the palm family found in tropical Africa. These rattans are uncommon in cultivation and poorly understood by taxonomists;. Closely related to ''Laccosperma'', they differentiated by the ...

'' and ''

Laccosperma ''Laccosperma'' is a clustering genus of flowering plant in the family palm found in tropical Africa. Poorly studied and rarely cultivated, they are closely related to the genus '' Eremospatha'' and with it form a tribe in the ''Calameae'' charac ...

'' in the

Ancistrophyllinae Ancistrophyllinae is a subtribe of plants in the family Arecaceae found in Africa. Genera in the subtribe are: *''Oncocalamus'' *'' Eremospatha'' *'' Laccosperma'' See also * List of Arecaceae genera This is a list of all the genera in ...

, 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 Calamoideae is a subfamily of flowering plant in the palm family found throughout Central America, South America, Africa, India, China, Southeast Asia and Australia. It is represented by 21 genera - containing nearly a quarter of all species in ...

with heavy

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

ion rates.Uhl, Natalie W. and Dransfield, John (1987) ''Genera Palmarum - A classification of palms based on the work of Harold E. Moore''. Lawrence, Kansas: Allen Press. / The

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

genus name combines "horn" and "capsule".Riffle, Robert L. and Craft, Paul (2003) ''An Encyclopedia of Cultivated Palms''. Portland: Timber Press. /

Description

The trunks are small, very spiny, and high climbing, becoming bare with age. All species form dense clusters with undivided or bifid juvenile

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

which become

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

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

hapaxanth Monocarpic plants are those that flower and set seeds only once, and then die. The term is derived from Greek (''mono'', "single" + ''karpos'', "fruit" or "grain"), and was first used by Alphonse de Candolle. Other terms with the same meaning are ...

s, the

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

emerges at the top of the stem, amongst reduced leaves, with male and female

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s, 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 In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

is spherical and covered in vertical rows of yellow to brown scales with one

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

Distribution and habitat

Strictly low land

rain forest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainforest ...

inhabitants, they are found in

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

ial west

References

External links

''Oncocalamus'' on NPGS/GRINGBIF portalFairchild Guide to Palms: ''Oncocalamus''
{{Taxonbar, from=Q143643 Calamoideae Arecaceae genera Flora of Africa