A Comparative Palynologic Study of Chaetanthera (Asteraceae, Mutisieae) and Allied Genera
Chaetanthera is a South American genus of 43 species in seven subgenera. Pollen grain morphology of 39 species of Chaetanthera and allied genera of Mutisiinae was surveyed using light and electron microscopy. Two palynologic groups are distinguished in Chaetanthera, defined as types I and II, the latter with the subtypes II 1 and II 2. The groups are supported by additional morphological and habit characteristics. Type I has pollen with a thinner exine (usually 5–7 μm thick), subrectangular shape, nexine outline elliptic to subrectangular, and medium-sized; type II has pollen with a thicker exine (11–18 μm thick), elliptic shape, nexine outline dumbbell-shaped, and large-sized. Subtype II 1 has columellae in the ectosexine, whereas subtype II 2 has a compact ectosexine. A palynologic alliance is established among the mutisiean genera Aphyllocladus, Gypothamnium, and Plazia (Plazia group), species of Onoseris and Urmenetea (Onoseris group), Brachyclados, Chaetanthera, Lulia, Mutisia, and Pachylaena (Mutisia group), Gerbera, Trichocline, and Uechtritzia (part of the Gerbera group), and Hyaloseris and Dinoseris on the basis of pollen similarities. These generic groups are defined by the habit and floral and fruit features, and the pollen structure is mainly useful to establish relationships among the groups. In this scheme the Mutisia group, which includes Chaetanthera, approaches the Onoseris and Gerbera groups.
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Document Type: Regular Paper
Publication date: 01 July 2004
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