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Michaux's saxifrage

storm saxifrage

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

basal;

petiole somewhat flattened, 2–6 cm;

blade oblanceolate, 2–12 cm, thin, basecuneate to ± attenuate, margins usually 15+-toothed (teeth large, lobelike), densely long glandular-ciliate, surfaces hairy.

basal;

petiole indistinct (leaves appearing sessile), flattened, 2–8+ mm;

blade oblanceolate to obovate, 4–10(–30) mm, fleshy, base cuneate to attenuate, margins entire or minutely denticulate, eciliate, (apex acute to obtuse or rounded), surfaces ± glabrous; (venation pinnate or palmate).

Inflorescences

30+-flowered, very open, lax thyrses, (flowers rarely replaced by bulbils), 10–40 cm, densely tangled, purple-tipped stipitate-glandular; (bracts leaflike, gradually reduced distally).

5–15(–20)-flowered, congested thyrses, 3–10(–15) cm, glabrous or sparsely purple-tipped stipitate-glandular.

Flowers

slightly bilaterally symmetric;

sepals reflexed, oblong to elliptic;

petals white, 3 with 2 basal yellow spots, 2 without spots, oblanceolate to spatulate, clawed, 3–4.5 mm, longer than sepals;

filaments linear, flattened;

pistils connate 1/2+ their lengths;

ovary superior.

sepals spreading, ovate;

petals white, not spotted, linear to obovate, clawed, to 1.5 mm, shorter than sepals;

filaments linear, flattened;

pistils connate to 1/2 their lengths;

ovary inferior.

Capsules

green to yellow, sometimes purple tinged, valvate

reddish purple, valvate.

2n

= 10.

Micranthes petiolaris

Micranthes tempestiva

Phenology Flowering late spring–early autumn. Flowering summer.
Habitat Wet ledges, boulderfields, and rocky slopes, usually in thin soil over rock Rocky ledges, slopes, or snow-bed meadows
Elevation 500-2100 m (1600-6900 ft) 2400-3200 m (7900-10500 ft)
Distribution
from FNA
GA; KY; MD; NC; SC; TN; VA; WV
[WildflowerSearch map]
[BONAP county map]
from FNA
MT
[BONAP county map]
Discussion

Micranthes petiolaris (Rafinesque) Brouillet & Gornall is an isonym.

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

Of conservation concern.

Micranthes tempestiva is known only from the Bitterroot Mountains and Anaconda Range.

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

Source FNA vol. 8, p. 58. FNA vol. 8, p. 69.
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. 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. 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. rufidula, M. spicata, M. stellaris, M. subapetala, M. tenuis, M. texana, M. tischii, M. tolmiei, M. unalaschcensis, M. virginiensis
Synonyms Hexaphoma petiolaris, Saxifraga michauxii, Saxifraga petiolaris Saxifraga tempestiva
Name authority (Rafinesque) Bush: Amer. Midl. Naturalist 11: 225. 1928 , (Elvander & Denton) Brouillet & Gornall: J. Bot. Res. Inst. Texas 1: 1021. 2007 ,
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