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Geum rossii var. depressum

Ross' avens

Habit Plants subscapose.
Stems

4–28 cm, glabrous or downy, hairs to 1 mm, sometimes septate-glandular.

Leaves

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.

Inflorescences

1–3(–4)-flowered.

Pedicels

woolly, sometimes glandular.

Flowers

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.

Fruiting tori

sessile, glabrous.

Fruiting styles

wholly persistent, not geniculate-jointed, 2–5(–10) mm, apex not hooked, glabrous throughout or pilose only at base.

2n

= 56.

Geum rossii

Phenology Flowering summer.
Habitat Alpine and arctic tundra, rocky slopes, often in gravelly or peaty soil
Elevation 0–4000 m (0–13100 ft)
Distribution
from FNA
AK; AZ; CO; ID; MT; NM; NV; OR; UT; WA; WY; BC; NT; NU; YT; Greenland; e Asia (Russian Far East)
[BONAP county map]
Discussion

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.)

Source FNA vol. 9, p. 63.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Colurieae > Geum
Sibling taxa
G. aleppicum, G. calthifolium, G. canadense, G. geniculatum, G. glaciale, G. laciniatum, G. macrophyllum, G. peckii, G. radiatum, G. rivale, G. rossii, G. schofieldii, G. triflorum, G. urbanum, G. vernum, G. virginianum
Synonyms Sieversia rossii, Acomastylis rossii, G. rossii var. depressum, G. rossii var. turbinatum, G. turbinatum, S. gracilipes
Name authority (R. Brown) Seringe: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 2: 553. (1825)
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