Braya humilis subsp. humilis |
Braya |
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dwarf braya |
northern-rockcress |
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Habit | Perennials; (sometimes pulvinate, caudex simple or many-branched); scapose or not; usually pubescent or pilose, sometimes glabrous, trichomes short-stalked, forked, subdendritic, or submalpighiaceous, mixed with simple ones (rarely exclusively). | |||||||||||||||||||||||||
Stems | ascending to erect, branched or unbranched, 0.4–3.3 dm, sparsely to moderately pubescent. |
erect to decumbent or ascending, unbranched or branched. |
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Leaves | blade margins sinuate-dentate, shallowly pinnatifid, or entire, surfaces moderately pubescent. |
basal and, sometimes, cauline; petiolate or sessile; basal rosulate, petiolate, blade margins entire, sinuate, dentate, or, rarely, pinnately lobed; cauline usually absent, rarely few present, (sub)sessile, blade margins usually entire, rarely dentate or pinnately lobed. |
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Racemes | (corymbose, sometimes bracteate basally or throughout), elongated or not in fruit. |
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Flowers | petals white, pink, or purple, 2.5–6.9(–7.5) × (0.7–)0.9–4(–4.2) mm. |
sepals [sometimes persistent], oblong [ovate], lateral pair not saccate basally (sometimes slightly so in B. humilis and B. linearis); petals white, pink, or purple [rarely pale yellow], obovate, oblanceolate, or spatulate, (slightly to much longer than sepals), claw distinct or not, (shorter than sepal, apex obtuse or rounded); stamens tetradynamous; filaments dilated or not basally; anthers ovate or oblong, (apex usually obtuse, sometimes apiculate); nectar glands (4), lateral, 1 on each side of lateral stamen. |
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Fruiting pedicels | erect, divaricate, or ascending, slender (much narrower than fruit). |
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Fruits | usually fertile and fully developed, somewhat torulose, 0.6–1.2(–1.3) mm wide; septum not fenestrate or split longitudinally. |
siliques or silicles, sessile, linear, oblong, cylindrical, oval-elliptic, ovoid, lanceoloid, lanceoloid-subulate, or globose, smooth or torulose, terete or slightly latiseptate; valves each often with prominent midvein, glabrous or pubescent; replum rounded; septum complete, (membranous, translucent); ovules (5–)14–44 per ovary; stigma capitate, entire or slightly 2-lobed. |
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Seeds | plump, not winged, oblong or ovoid; seed coat (minutely reticulate), not mucilaginous when wetted; cotyledons incumbent. |
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x | = 7. |
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2n | = 28, 42, 56, 70. |
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Braya humilis subsp. humilis |
Braya |
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Phenology | Flowering May–Jul. | |||||||||||||||||||||||||
Habitat | Sandy, gravelly soil along streams, lakeshores, roadsides, moraines, open stony slopes, dolomite cliffs and slopes, limestone ledges, solifluction soils | |||||||||||||||||||||||||
Elevation | 0-4000 m (0-13100 ft) | |||||||||||||||||||||||||
Distribution |
AK; CO; MI; MT; VT; WY; AB; BC; MB; NF; NT; NU; ON; QC; YT; Greenland; e Asia; c Asia |
North America; n Europe; Asia |
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Discussion | Subspecies humilis is extremely variable morphologically. In a general way, morphological form correlates with ploidy level, e.g., tetraploids, octoploids, and decaploids tend to be short in stature with small leaves. Hexaploids are less predictable. They range from short plants with small leaves to large, robust, multi-branched plants with large, pinnatifid leaves. Attempting to segregate most morphological forms of Braya humilis into logical infraspecific taxa is an exercise in futility. Populations that appear distinctive in the field almost always blur imperceptibly into the larger subsp. humilis continuum when compared with other populations from across the range of distribution. Subspecies humilis is broadly distributed on calcareous substrates in arctic, subarctic, alpine, and boreal regions of North America and Asia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species 17 (7 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 7, p. 549. | FNA vol. 7, p. 546. | ||||||||||||||||||||||||
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Synonyms | Arabidopsis novae-angliae, B. humilis var. abbei, B. humilis subsp. arctica, B. humilis var. arctica, B. humilis var. interior, B. humilis var. laurentiana, B. humilis var. leiocarpa, B. humilis var. novae-angliae, B. humilis subsp. richardsonii, B. humilis subsp. ventosa, B. humilis var. ventosa, B. intermedia, B. novae-angliae, B. novae-angliae subsp. abbei, B. novae-angliae var. interior, B. novae-angliae var. laurentiana, B. novae-angliae subsp. ventosa, B. richardsonii, Pilosella novae-angliae, Pilosella richardsonii, Torularia humilis subsp. arctica | Platypetalum | ||||||||||||||||||||||||
Name authority | unknown | Sternberg & Hoppe: Denkschr. Königl.-Baier. Bot. Ges. Regensburg 1(1): 65. (1815) | ||||||||||||||||||||||||
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