Adelonema is a genus of flowering plants in the family Araceae (the arum family), placed in the order Alismatales. It comprises roughly 16 species of clump-forming evergreen perennials native to the Neotropics — principally Central America and northern South America, including Panama, Colombia, Ecuador, Peru, and Brazil.
Plants in the genus share the characteristic Araceae body plan: mainly heart-shaped to arrowhead-shaped leaves borne on petioles, and tiny, petalless flowers arranged on a spadix and enclosed in a greenish spathe that is typically hidden beneath the foliage. The genus is morphologically similar to the Old World genus Homalomena, of which it was long considered a part. Adelonema was originally described by Schott in 1860 to accommodate the neotropical species of Homalomena, and several authorities treated it as a synonym for most of the 20th century before it was reinstated as a distinct genus, with the transfer formalised by S.Y. Wong and Croat. The separation reflects a biogeographical divide: Homalomena is strictly an Old World genus of tropical Asia, while Adelonema represents its New World ecological counterpart.
Notable species include Adelonema wendlandii, Adelonema wallisii, Adelonema erythropus, and Adelonema picturatum, several of which are cultivated as foliage plants for their ornamental leaves.
Etymology
The name Adelonema was coined by the Austrian botanist Heinrich Wilhelm Schott in 1860. The genus was established to group the neotropical species that had previously been placed in Homalomena, a name itself derived from a mistranslated Malayan vernacular term (combining Greek homalos, meaning flat, and mene, meaning moon). The reinstatement of Adelonema as distinct from Homalomena reflects the geographical separation between Old World and New World species.
Distribution
Adelonema species are native to the Neotropics, distributed across Central America (including Panama) and northern South America (Colombia, Ecuador, Peru, Brazil, and adjacent regions). The genus occupies the New World ecological niche filled in tropical Asia by the related genus Homalomena.
Taxonomy Notes
Adelonema was originally described by Schott (1860) and for much of the 20th century was treated as a synonym of Homalomena. It was subsequently reinstated as a distinct genus based on its strictly neotropical distribution, with most species transferred from Homalomena by S.Y. Wong and Croat. GBIF records the synonymous usage as "Adelonema Schott, 1860". The genus belongs to the family Araceae, order Alismatales.
