''Ravenea'' is a genus of 20 known species of palms, all native to

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

and the

Comoros The Comoros,, ' officially the Union of the Comoros,; ar, الاتحاد القمري ' is an independent country made up of three islands in southeastern Africa, located at the northern end of the Mozambique Channel in the Indian Ocean. It ...

.Kew World Checklist of Selected Plant Families
/ref> They are small to large,

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

palms, with solitary, robust grey stems, swollen at base and gradually tapering upward. The species vary greatly in size, with ''R. hildebrandtii'' and ''R. nana'' only reaching 4 m, while ''R. robustior'' and ''R. sambiranensis'' both reach 30 m. The

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 ...

are up to 2–5 m long, pinnately compound, reduplicate, erect at first then arching, twisted near the apex; with numerous crowded narrow ribbed leaflets. 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 ...

is short, borne among the leaves; 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 a red

drupe In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...

. One particular species, '' Ravenea rivularis'', is commonly cultivated as a houseplant and grown indoors all over the world. However, it is actually considered a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

in its wild habitat with fewer than 900 trees growing naturally.

Species

Most of the species are

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

. Species such as ''R. moorei'' are critically so, with only two specimens known, last seen in 1993
IUCN report
. ''R. louvelii'' is little better off, with fewer than 25 plants known
IUCN report
. Overall, less than 50 trees of several species are still alive. Historical data indicates that populations are still decreasing for most, except for ''Ravenea sambiranesis'' and '' Ravenea madagascariensis''. The species listed as critically endangered will most likely become

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 ...

this century unless measures are taken to cultivate new trees and protect their habitats from being disrupted by

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...

and

water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...

. Even if as few as a dozen trees of each species were planted on ideal, protected land where they could reproduce, it would give each species a much better chance for survival.

Cultivation and uses

'' Ravenea rivularis'' (majesty palm) is widely cultivated in subtropical regions, and it is sold commercially as a houseplant. It is an adaptable palm that looks somewhat similar to the ever-popular

Queen palm ''Syagrus romanzoffiana'', the queen palm or cocos palm, is a palm native to South America, introduced throughout the world as a popular ornamental garden tree. ''S. romanzoffiana'' is a medium-sized palm, quickly reaching maturity at a height o ...

. It is a very large palm with a large, untidy crown. It has symmetrical leaves and develops an attractive swollen base of the trunk. Majesty palms prefer full sun, plenty of water, and high humidity to ensure healthy growth. It is tolerant of different soil types. Propagation is by seeds, which germinate in 2–3 months. Ravenea rivularis 2zz

References

Fairchild Tropical Botanic Garden: ''Ravenea''RBG Kew: ''Ravenea''
{{Taxonbar, from=Q144677 Arecaceae genera Flora of the Western Indian Ocean Dioecious plants