Ivesia sect. Stellariopsis
Rosaceae subfam. rosoideae
(1–)1.5–4 dm.
alternate, rarely opposite, pinnately compound, sometimes simple or palmately compound;
stipules present, rarely absent.
very tightly cylindric (mousetail-like);
stipules present;
leaflets tightly overlapping, individually scarcely distinguishable, lobed to base, sometimes entire, densely hairy;
terminal leaflets indistinct.
1–3, not paired;
blade relatively well developed.
open, flowers arranged individually.
remaining ± straight.
hypanthium shallowly campanulate;
petals not medially reflexed, white, short-clawed, apex rounded;
stamens 15, anthers shorter than wide, dehiscing by subterminal pores to short lateral slits;
carpels 1.
torus usually enlarged, sometimes small or absent;
carpels 1–260(–450), distinct, free, styles distinct, rarely connate (Roseae);
ovules 1(or 2), collateral (Rubeae) or superposed (Fallugia, Filipendula).
achenes or aggregated achenes sometimes with fleshy, urn-shaped hypanthium or enlarged torus, sometimes aggregated drupelets;
styles persistent or deciduous, not elongate (elongate but not plumose in Geum).
vertical, smooth, not carunculate.
= 7(8).
Ivesia sect. Stellariopsis
Rosaceae subfam. rosoideae
Species 1.
P. A. Rydberg (1898) recognized Stellariopsis at the generic level primarily on the basis of the obcordate anthers, which apparently open by terminal pores, as well as the single carpel, mousetail-like leaves, diffuse inflorescence, and flowers intermediate between Ivesia and Potentilla. J. Soják (2008) argued that the anther character alone justifies generic status. Examination of a series of flowers shows that porelike dehiscence is largely a result of the extreme shortness of the anthers relative to width, such that longer-than-average anthers approach a more typical dehiscence mode. The single carpel and mousetail-like leaves are consistent within the taxon, although both are found elsewhere in the genus (albeit not in the same species). The relatively large, maroon-tipped stipitate glands of the inflorescence branches, including the pedicel and hypanthium, are otherwise unknown in Ivesia.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Variation in the number of genera in subfam. Rosoideae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of some Potentilleae genera. Cyanogenic glycosides and sorbitol are absent in the subfamily.
Tribes 6, genera 28–35, species ca. 1600 (6 tribes, 26 genera, 302 species, including 1 hybrid, in the flora)
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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