Koehne (1893, pp. 224-226) distinguished two sections, Chaenopetalum and Orthopetalum (= section Cotoneaster), which were raised to subgenera by Klotz (1982). Subgenus Chaenopetalum has species with petals spreading and white when open. Subgenus Cotoneaster has species with petals erect or closed and pink to dark red (Fryer & Hylmoe 2009, pp. 14-15). However, Lo & Donoghue (2012, p. 234), in a DNA sequencing study of the Rosaceae subfamily Pyreae, found that "Within the Cotoneaster clade ... the species are divided into two well-supported subclades, which both contain species assigned to the two subgenera, Chaenopetalum and Cotoneaster (Fryer & Hylmoe 2009), implying that neither one is monophyletic." For instance, Cotoneaster franchetii and C. pannosus are vegetatively very similar and both are in the same clade, but they are assigned to different subgenera because their flowers differ, one with erect petals, the other spreading. Lo & Donoghue's (2012) analysis suggests that two pollination syndromes have arisen repeatedly rather than once, as implied by the subgeneric classification above. That classification is therefore not used here.
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|Last updated||November 27, 2017|
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