Braya humilis subsp. maccallae |
Braya humilis subsp. humilis |
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dwarf braya, maccall's dwarf braya, mccalla's dwarf braya |
dwarf braya |
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Stems | ascending to erect, often unbranched, 0.4–2.3 dm, moderately pubescent. |
ascending to erect, branched or unbranched, 0.4–3.3 dm, sparsely to moderately pubescent. |
Leaves | blade margins entire or, sometimes, sinuate-dentate, surfaces glabrescent to moderately pubescent. |
blade margins sinuate-dentate, shallowly pinnatifid, or entire, surfaces moderately pubescent. |
Flowers | petals white, (4.4–)4.9–6.7(–7.2) × (2.1–)2.3–4(–4.2) mm. |
petals white, pink, or purple, 2.5–6.9(–7.5) × (0.7–)0.9–4(–4.2) mm. |
Fruits | often abortive, somewhat torulose, 0.7–1.2 mm wide when fully developed; septum not fenestrate or split longitudinally. |
usually fertile and fully developed, somewhat torulose, 0.6–1.2(–1.3) mm wide; septum not fenestrate or split longitudinally. |
2n | = 28. |
= 28, 42, 56, 70. |
Braya humilis subsp. maccallae |
Braya humilis subsp. humilis |
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Phenology | Flowering May–Jul. | Flowering May–Jul. |
Habitat | Sandy gravelly riverbanks and floodplains, sometimes on slopes and glacial moraines | Sandy, gravelly soil along streams, lakeshores, roadsides, moraines, open stony slopes, dolomite cliffs and slopes, limestone ledges, solifluction soils |
Elevation | 1500-3000 m (4900-9800 ft) | 0-4000 m (0-13100 ft) |
Distribution |
AB; BC |
AK; CO; MI; MT; VT; WY; AB; BC; MB; NF; NT; NU; ON; QC; YT; Greenland; e Asia; c Asia |
Discussion | Subspecies maccallae differs from subspp. elesmerensis and humilis in having leaf margins mostly entire, flowers exceptionally large, and a high percentage of abortive fruit. Cauline leaves are much reduced and arise from the base of the stem, giving an almost acaulescent appearance to the plant. Breeding studies (J. G. Harris 1985) indicate that subspp. maccallae and porsildii are self-incompatible, while most subspecies of Braya humilis are strongly autogamous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 7, p. 550. | FNA vol. 7, p. 549. |
Parent taxa | ||
Sibling taxa | ||
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 | |
Name authority | J. G. Harris: Novon 16: 346. (2006) | unknown |
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