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Agatea

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Agatea
Agatea violaris
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malpighiales
Family: Violaceae
Subfamily: Violoideae
Tribe: Violeae
Genus: Agatea
A.Gray[1][2][3]
Type species
Agatea violaris
A.Gray[4]
Species
Synonyms[2]

Agatea is a genus of flowering plants in the violet family Violaceae, with seven accepted species, found in New Guinea and New Caledonia.

Description

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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]

Taxonomy

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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]

Etymology

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The genus is named for the botanical draughtsman on the expedition, Alfred T. Agate.[8]

Species

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Although estimates of the number of species has varied between one[12] and ten,[7] there are seven[14] or eight[2] generally-accepted species.

New species, e.g. A. lecointei and A. veillonii, continue to be discovered, these two in New Caledonia in 2001.[12]

Distribution and habitat

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

References

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  1. ^ a b WFO 2019.
  2. ^ a b c d POTWO 2020.
  3. ^ IPNI 2020.
  4. ^ a b Tropicos 2020.
  5. ^ a b c Ballard et al 2013.
  6. ^ a b Byng 2014.
  7. ^ a b c Wahlert et al 2014.
  8. ^ a b Gray 1852.
  9. ^ Gray 1854.
  10. ^ Bentham & Hooker 1862.
  11. ^ a b de Paula-Souza & Pirani 2014.
  12. ^ a b c d e f Munzinger 2001.
  13. ^ de Paula-Souza & Souza 2003.
  14. ^ Christenhusz et al 2017.
  15. ^ a b c INPN 2020.

Bibliography

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Books
Articles
Websites
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