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Concept
Hippeastreae
Résumé
Hippeastreae is a tribe of plants belonging to the subfamily Amaryllidoideae of the Amaryllis family (Amaryllidaceae). Species in this tribe are distributed in South America. Flowers are large and showy, zygomorphic, with the stamens in varying lengths, inflorescence bracts are often fused basally (along one side). The seeds are flattened, winged or D-shaped. Reported basic chromosome numbers are x= 8-13, 17, and higher. All the species in this tribe present a remarkable aesthetic interest and horticultural value.
Meerow et al. (1999) provide a history of the treatment of the genera of Amaryllidaceae, including Hippeastreae, from the mid-twentieth century. While morphological phylogeny has been frustrated by the perversive homoplasy typical of the Amaryllidaceae, application of molecular phylogenetics to the Amaryllidaceae did not indicate clear tribal divisions but rather broad biogeographical clades. However the American clade resolved the tribe Hippeastreae. A later examination of the deeper relationships of the American genera suggested the two subclades, Andean and hippeastroid and within the latter separated the Brazilian Griffineae as sister to the remaining hippeastroids. The larger and more diverse grouping of hippeastroids formed two smaller monophyletic groups. The smaller contained Hippeastrum (with the exception of Hippeastrum blumenavium), but also a Rhodophiala. With the exception of Rodophilia (Brazil) all specimens were from Chile and Argentina. The second group corresponded to those genera variously included in tribe Zephyrantheae (Traub) or subtribe Zephyranthinae (Müller-Doblies), but only including some Zephyranthes species. The hippeastroid clade is predominantly diploid and extra-Andean by comparison to the Andean clade which is predominantly tetraploid, and contain those genera traditionally included in Hippeastreae. The precise position of Griffineae remained unresolved since its sister status to Hippeastrae was weak, leaving the possibility that it could be sister to the whole American clade.
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