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Idaho saxifrage

rusty-hair saxifrage

Habit Plants solitary or tufted, with bulbils on caudices. Plants solitary or in groups, with bulbils on caudices, or rhizomatous.
Leaves

basal;

petiole flattened, 1–5 cm;

blade ovate to elliptic, 1–4 cm, ± fleshy, base attenuate, margins shallowly serrate to dentate (teeth usually to 1 mm), sparsely ciliate, surfaces tangled, reddish brown-hairy abaxially, glabrate adaxially.

basal;

petiole flattened, 4–8 cm;

blade ovate to elliptic, 1–4 cm, fleshy, base attenuate to ± truncate, margins serrate (15–30- toothed), eciliate, surfaces densely tangled, reddish brown-hairy abaxially, glabrous adaxially.

Inflorescences

15+-flowered, open thyrses, (flowers ± crowded at tips, becoming more open in fruit), 10–40 cm, purple-tipped stipitate-glandular.

15+-flowered, open, flat-topped thyrses, 5–20 cm, purple-tipped stipitate-glandular; (bracts often tangled brown-hairy).

Flowers

sepals reflexed, ovate to oblong;

petals white, with 2 basal yellow spots (often faded when dried), elliptic to ovate, clawed to nearly not clawed, 1–3.5 mm, ± equaling sepals;

filaments club-shaped, not petaloid, (equaling petals);

pistils distinct almost to base;

ovary superior, (to 1/3 adnate to hypanthium).

sepals spreading, ovate, (often tangled brown-hairy);

petals white, not spotted, ovate to elliptic, clawed, 2–4 mm, longer than sepals;

filaments linear, flattened to slightly club-shaped;

pistils distinct almost to base;

ovary superior, (to 1/3 adnate to hypanthium).

Capsules

green to reddish purple, folliclelike.

greenish to reddish purple, folliclelike.

2n

= 20.

= 20, 38, 56, 58.

Micranthes idahoensis

Micranthes rufidula

Phenology Flowering spring–early summer. Flowering late winter–summer.
Habitat Open ledges and slopes Wet to dry, rocky ledges
Elevation 500-2500 m (1600-8200 ft) 0-3000 m (0-9800 ft)
Distribution
from FNA
ID; MT; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Micranthes idahoensis appears to hybridize with M. occidentalis where their ranges overlap. Intermediates are abundant in some populations along the Idaho-Montana border and in Montana. This phenomenon may explain the range of filament shapes found in M. occidentalis, from flattened to sightly club-shaped. The issue of the status of M. idahoensis with respect to M. marshallii (D. L. Krause and K. I. Beamish 1972) is best deferred until a thorough study of the whole complex over its entire range is done.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 8, p. 64. FNA vol. 8, p. 62.
Parent taxa Saxifragaceae > Micranthes Saxifragaceae > Micranthes
Sibling taxa
M. apetala, M. aprica, M. bryophora, M. californica, M. calycina, M. careyana, M. caroliniana, M. eriophora, M. ferruginea, M. foliolosa, M. fragosa, M. gaspensis, M. gormanii, M. hieraciifolia, M. hitchcockiana, M. howellii, M. integrifolia, M. lyallii, M. marshallii, M. micranthidifolia, M. nelsoniana, M. nidifica, M. nivalis, M. nudicaulis, M. occidentalis, M. odontoloma, M. oregana, M. palmeri, M. pensylvanica, M. petiolaris, M. razshivinii, M. reflexa, M. rhomboidea, M. rufidula, M. spicata, M. stellaris, M. subapetala, M. tempestiva, M. tenuis, M. texana, M. tischii, M. tolmiei, M. unalaschcensis, M. virginiensis
M. apetala, M. aprica, M. bryophora, M. californica, M. calycina, M. careyana, M. caroliniana, M. eriophora, M. ferruginea, M. foliolosa, M. fragosa, M. gaspensis, M. gormanii, M. hieraciifolia, M. hitchcockiana, M. howellii, M. idahoensis, M. integrifolia, M. lyallii, M. marshallii, M. micranthidifolia, M. nelsoniana, M. nidifica, M. nivalis, M. nudicaulis, M. occidentalis, M. odontoloma, M. oregana, M. palmeri, M. pensylvanica, M. petiolaris, M. razshivinii, M. reflexa, M. rhomboidea, M. spicata, M. stellaris, M. subapetala, M. tempestiva, M. tenuis, M. texana, M. tischii, M. tolmiei, M. unalaschcensis, M. virginiensis
Synonyms Saxifraga idahoensis, Saxifraga marshallii subsp. idahoensis, Saxifraga marshallii var. idahoensis, Saxifraga occidentalis var. idahoensis Saxifraga aequidentata, Saxifraga occidentalis subsp. rufidula, Saxifraga occidentalis var. rufidula, Saxifraga rufidula
Name authority (Piper) Brouillet & Gornall: J. Bot. Res. Inst. Texas 1: 1020. 2007 , Small: in N. L. Britton et al., N. Amer. Fl. 22: 140. (1905)
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