Braya humilis subsp. ellesmerensis
Braya humilis
alpine northern-rockcress, dwarf braya, low braya, low northern-rockcress
usually ascending (prostrate in fruit), unbranched, 0.3–1.6 dm, moderately pubescent.
usually few to several from base, rarely simple, ascending or erect, rarely subdecumbent, (0.4–)0.8–2.5(–3.5) dm.
blade margins pinnatifid or entire, surfaces moderately pubescent.
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).
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.
petals white or purple-tinged, (3–)4–5.6 × (1.3–)2–3.3(–3.8) 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).
usually fertile and fully developed, not or weakly torulose, (1–)1.2–1.8(–2) mm wide;
septum often fenestrate (with circular perforations at regular intervals longitudinally or with a narrow, elliptical, longitudinal split at base or both).
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.
uniseriate, oblong, 0.6–0.9x 0.4–0.5 mm.
= 42.
Braya humilis subsp. ellesmerensis
Braya humilis
Prostrate fruiting stems, exceptionally broad, non-torulose fruits, and fenestrate silique septae distinguish subsp. ellesmerensis from other subspecies of Braya humilis. It is known only from northern Ellesmere Island.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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 |
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