The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links
Geum rossii var. depressum

Ross' avens

Habit Plants subscapose. Herbs, shrubs, or subshrubs.
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.

alternate, rarely opposite, pinnately compound, sometimes simple or palmately compound;

stipules present, rarely absent.

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.

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).

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.

Fruits

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).

x

= 7(8).

2n

= 56.

Geum rossii

Rosaceae subfam. rosoideae

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]
North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia
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.)

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.)

Source FNA vol. 9, p. 63. FNA vol. 9, p. 23. Author: Luc Brouillet.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Colurieae > Geum Rosaceae
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
Subordinate taxa
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) Arnott: Botany, 107. (1832)
Web links