Agatea

Lianas or reclining shrubs with lanceolate to ovate leaves. The flowers are in terminal pseudo-racemes or racemoids, with white corollas that are strongly zygomorphic (bilaterally symmetrical) with the very large bottom petal differentiated into a claw and blade and saccate (pouch like) at the base. On the five stamens, the filaments are weakly connate with the two lowest anthers weakly calcarate (spurred) and possessing a large dorsal connective appendage that is entire and oblong-ovate. In the gynoecium, the style is filiform (threadlike) to clavate (club like). The fruit is a thin to thick-walled capsule with 3 or 6 valves. There are two seeds per carpel, that are strongly flattened and encircled with a broad thin wing. The chromosome number is 2n=16.[5][6][7]

The genus Agatea was first described by Gray in 1852,[8] following the United States Exploring Expedition of 1838–1842, and therefore bears his name, A.Gray, as the botanical authority.[4] Gray's description was of the single species, Agatea violaris, which is thus the type species. His report was published in full in 1854.[9]

Early taxonomic schemes such as Bentham and Hooker (1862)[10] placed Agatea within subfamily Violoideae, tribe Violeae, subtribe Violinae.[6][11] For a while, the name Agatea was disputed, and Agation used instead, but this was resolved in favor of the former name.[12] The genus has also been subject to over-description resulting from polymorphism.

Agatea is one of four lianescent genera in Violaceae, together with Calyptrion Ging., Anchietea A.St.-Hil. and the more recently discovered (2003) Hybanthopsis Paula-Souza.[13] In earlier classifications primarily based on floral morphology these were distributed among separate subtribes, but molecular phylogenetic studies has now grouped them together into a single lianescent clade, one of four within the family. Earlier schemes had placed Agatea within subfamily Violoideae, tribe Violeae, subtribe Hybanthinae, with Hybanthopsis but Calyptrion and Anchietea in subtribe Violinae.[5][11]

Agatea are native to New Guinea and some nearby South Pacific islands including New Caledonia, and are found in monsoon forests.[5][2]