Geum rossii
Geum radiatum
alpine avens, Ross' avens, slender stem avens
Appalachian avens, spreading avens
4–28 cm, glabrous or downy, hairs to 1 mm, sometimes septate-glandular.
10–45(–60) cm, densely hirsute proximally to puberulent distally.
basal 3–13 cm, blade pinnate to interruptedly pinnate, major leaflets 13–26, alternating with 0–14 minor ones, terminal leaflet slightly larger than major laterals;
cauline 0.7–2 cm, stipules adnate to leaf, indistinguishable from pair of lobes, blade bractlike, not resembling basal, alternate, simple, pinnatifid to 3-fid.
basal 10–30 cm, blade strongly lyrate-pinnate, sometimes simple, major leaflet 1, minor leaflets 1–6, terminal leaflet much larger than minor laterals;
cauline 1.2–4 cm, stipules not evident, blade bractlike, not resembling basal, simple.
1–3(–4)-flowered.
3–10-flowered.
woolly, sometimes glandular.
glandular-hairy.
erect;
epicalyx bractlets 1.5–7 mm;
hypanthium green, slightly purple-tinged to strongly purple;
sepals erect to erect-spreading, 3–10 mm;
petals spreading, yellow, obovate to nearly orbiculate, 5–12(–17) mm, longer than sepals, apex broadly rounded to irregularly emarginate.
erect;
epicalyx bractlets 2–5 mm;
hypanthium green;
sepals spreading in flower, erect in fruit, 6–10 mm;
petals spreading, yellow, orbiculate to obcordate, 9–16 mm, longer than sepals, apex emarginate.
sessile, glabrous.
sessile, glabrous.
wholly persistent, not geniculate-jointed, 2–5(–10) mm, apex not hooked, glabrous throughout or pilose only at base.
wholly persistent, not geniculate-jointed, 8–12 mm, apex not hooked, pilose and stipitate-glandular in basal 1/3.
= 56.
= 42.
Geum rossii
Geum radiatum
The variability accommodated here in Geum rossii was distributed by earlier monographers such as P. A. Rydberg (1913b) and F. Bolle (1933) among a half dozen species. W. Gajewski (1957) reduced them to two species, G. rossii and G. turbinatum; most recent taxonomists have recognized the two taxa as subspecies or varieties of a single species. The large geographic discontinuity between the Rocky Mountain and arctic ranges makes it easy for those wishing to follow this tradition. No one morphologic character or combination of characters neatly separates the arctic plants from those of the Rockies.
Where their ranges overlap in Alaska, Geum rossii hybridizes with G. calthifolium to form sterile plants known as G. ×macranthum (Kearney ex Rydberg) B. Boivin; see discussion under 4. G. schofieldii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Geum radiatum is closely related to G. calthifolium and G. peckii. The morphologic differences among them are slight compared to the discontinuities separating other Geum species. On the basis of morphology it would be possible to combine all three in a single species. Yet they occupy distinct ranges separated by a minimum of 1200 km. Traditionally, they have been treated as separate species, and recently I. G. Paterson and M. Snyder (1999) reported molecular genetic evidence for continuing to recognize G. peckii and G. radiatum as separate species.
Geum radiatum is listed as an endangered species by the U.S. Fish and Wildlife Service.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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