Braya humilis
Braya glabella
alpine northern-rockcress, dwarf braya, low braya, low northern-rockcress
alpine braya, smooth northern-rockcress
usually few to several from base, rarely simple, ascending or erect, rarely subdecumbent, (0.4–)0.8–2.5(–3.5) dm.
simple or few to several from base, ascending or erect, rarely decumbent to prostrate, (0.1–)0.3–1.7(–2.3) dm.
blade obovate, spatulate, oblanceolate, oblong, or sublinear, (0.3–)0.5–2(–3.5) cm × 1–8(–10) mm, base attenuate or cuneate, margins entire, sinuate-dentate, or pinnatifid, apex acute or obtuse, (surfaces sparsely to densely pubescent or, rarely, glabrous).
blade (often somewhat fleshy), linear-oblanceolate to broadly spatulate, (0.4–)0.8–6(–7.9) cm × (0.3–)0.6–4(–6) mm, base (membranous), broadly expanded near point of attachment, margins usually entire, sometimes weakly dentate with 1 or 2 teeth per side, apex obtuse, (often with a tuft of long, simple hairs, surfaces sparsely to moderately pubescent).
3 or more;
blade similar to basal, smaller distally, distalmost sessile or subsessile. (Racemes bracteate proximally, very rarely throughout, elongated in fruit.) Fruiting pedicels erect, ascending, or divaricate, (2.5–)3–8(–12) mm.
0 or 1 (or a leaflike bract subtending proximalmost pedicel). (Racemes elongated or not in fruit.) Fruiting pedicels ascending-erect to divaricate, (0.9–)1.9–7.5(–8.6) mm.
sepals 2–3 × 0.8–1.2 mm, (sometimes slightly saccate basally);
petals white, pink, or purple, (broadly obovate or spatulate), 3–5(–8) × (1–)1.5–2.5(–4) mm, (apex rounded);
filaments 2–3(–4) mm;
anthers oblong, 0.4–0.7mm, (apex apiculate).
sepals (1.6–)1.9–3.7 × (0.7–)1–2 mm;
petals white or purplish (broadly obovate or spatulate), (2.1–)2.4–4.5(–4.7) × (0.7–)1–3(–3.2) mm, (apex rounded);
filaments 1.7–2.2 mm;
anthers oblong, 0.3–0.5 mm.
linear, torulose or not, (mostly straight), (0.9–)1.2–2.5(–3.2) cm × 0.6–1.8(–2) mm (uniform in width);
valves pubescent or, rarely, glabrescent, trichomes submalpighiaceous, rarely mixed with fewer, simple ones;
septum fenestrate or not;
ovules 20–44 per ovary;
style 0.3–0.8(–1) mm;
stigma entire or strongly 2–lobed.
oval-elliptic, oblong-elliptic, oblong, or oblong-lanceoloid, sometimes slightly torulose, (straight or somewhat curved), (0.3–)0.5–1.2(–1.5) cm × (0.8–)1.1–3(–3.6) mm;
valves sparsely to densely pubescent or glabrous, trichomes simple or 2 (or 3)-forked;
septum margin not expanded or not basally;
ovules (5–)16–20 per ovary;
style (0.3–)0.5–1.8(–2) mm;
stigma entire or strongly 2-lobed, (narrow or broad).
uniseriate, oblong, 0.6–0.9x 0.4–0.5 mm.
biseriate, oblong, (0.7–)0.9–1.6 × 0.4–0.8(–0.9) mm.
Braya humilis
Braya glabella
Subspecies 4 (4 in the flora).
Braya humilis was recognized in Asian floristic accounts as a member of Neotorularia Hedge & J. Léonard (= Torularia O. E. Schulz), but molecular studies (S. I. Warwick et al. 2004) clearly support its assignment to Braya, as done by all North American authors (e.g., M. L. Fernald 1918; E. C. Abbe 1948; T. W. Böcher 1956, 1973; J. G. Harris 1985; R. C. Rollins 1993). The species is highly variable in leaf shape and margin, flower size and color, pubescence, fruit length and orientation, chromosome number, and length of the bracteate portion of the raceme. Occurrence of “races” with various ploidy levels is one of the reasons for variability that led to recognition of infraspecific taxa. The synonymy below pertains only to North America, with nearly as many names given to the Asian variants. Numerous morphological extremes were described in North America, Russia, and China, but most of those represent only part of an otherwise continuous variation. For example, fully bracteate racemes, though rare, appear sporadically in populations that otherwise have racemes only basally bracteate. Three morphological forms are more sharply distinct from the general subsp. humilis amalgam and seem to have some biological significance. All of them are restricted to areas in or near regions believed to have served as glacial refugia during the Pleistocene. They are recognized here as additional subspecies.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies 3 (3 in the flora).
Braya glabella is extremely variable, sometimes even within a population, and the species has often been split into taxa based primarily on fruit attributes. When the species is examined from its entire range, the perceived morphological gaps blur into a bewildering array of overlapping forms. On the basis of morphological and molecular evidence (S. I. Warwick et al. 2004) it is difficult to justify the recognition of more than one species in this very plastic group, but it does seem useful to divide the species into three fairly distinctive subspecies. Some populations will be readily separable into one of these subspecies, but others will likely defy unequivocal placement, particularly those from areas where the ranges of the subspecies meet.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Fruits (1-)1.2-1.8(-2) mm wide, not or weakly torulose; stems unbranched, ascending (prostrate in fruit). | subsp. ellesmerensis |
1. Fruits 0.6-1.2(-1.3) mm wide, usually somewhat torulose; stems unbranched or branched, ascending to erect | → 2 |
2. Petals 2.5-6.9(-7.5) mm; fruits usually fertile and fully developed; leaf blade margins often sinuate-dentate, pinnatifid, or entire. | subsp. humilis |
2. Petals (4.4-)4.9-6.9(-7.2) mm; fruits often abortive; leaf blade margins entire or sinuate-dentate, not pinnatifid | → 3 |
3. Leaves and stems glabrescent or moderately pubescent. | subsp. maccallae |
3. Leaves and stems densely pubescent. | subsp. porsildii |
1. Fruits oblong to narrowly oblong-lanceoloid, 3.5-8.3 times as long as wide; racemes often loosely elongated in fruit. | subsp. glabella |
1. Fruits oval-elliptic to oblong-elliptic, rarely broadly oblong-lanceoloid, 2.5-3.7 times as long as wide; racemes not elongated in fruit, often compact | → 2 |
2. Stems decumbent to prostrate, sometimes weakly ascending; leaf blades not fleshy, to 6 mm wide; fruits 0.8-1.2 cm; styles 0.8-1.8 mm. | subsp. prostrata |
2. Stems ascending to erect; leaf blades often fleshy, to 4 mm wide; fruits 0.5-1 cm; styles 0.5- 1.2 mm. | subsp. purpurascens |
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