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dwarf braya

northern-rockcress

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.

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.

Racemes

(corymbose, sometimes bracteate basally or throughout), elongated or not in fruit.

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.

Fruiting pedicels

erect, divaricate, or ascending, slender (much narrower than fruit).

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.

Seeds

plump, not winged, oblong or ovoid;

seed coat (minutely reticulate), not mucilaginous when wetted;

cotyledons incumbent.

x

= 7.

2n

= 28, 42, 56, 70.

Braya humilis subsp. humilis

Braya

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
from FNA
AK; CO; MI; MT; VT; WY; AB; BC; MB; NF; NT; NU; ON; QC; YT; Greenland; e Asia; c Asia
[BONAP county map]
from USDA
North America; n Europe; Asia
[BONAP county map]
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.)

Key
1. Plants not scapose; cauline leaves (1 or) 2-4; fruits linear; seeds usually uniseriate, rarely weakly biseriate
→ 2
1. Plants scapose; cauline leaves 0 or 1 (or with leaflike bract subtending proximalmost pedicel); fruits ovoid, globose, oval-elliptic, oblong, oblong-elliptic, oblong-lanceoloid, or lanceoloid-subulate, not linear; seeds usually biseriate (uniseriate in B. fernaldii and, sometimes, B. longii)
→ 3
2. Cauline leaves 3 or more; basal leaves (0.3-)0.5-2(-3.5) cm × 1-8(-10) mm; racemes elongated in fruit; fruits (0.9-)1.2-2.5(-3.2) cm
B. humilis
2. Cauline leaves 1-4; basal leaves 0.5-3 cm × 0.5-2(-3) mm; racemes not elongated in fruit; fruits (0.5-)0.9-1.2(-1.4) cm.
B. linearis
3. Fruits ovoid or globose
→ 4
3. Fruits oval-elliptic, oblong, oblong-elliptic, oblong-lanceoloid, or lanceoloid-subulate
→ 5
4. Petals 4.7-6.6 × 3-5.1 mm; styles 1.2-2(-2.5) mm; stems erect to ascending.
B. pilosa
4. Petals 2-3.7 × 1-1.5 mm; styles obsolete to 0.7(-1) mm; stems usually decumbent to prostrate, sometimes ascending.
B. thorild-wulffii
5. Fruits oval-elliptic, oblong-cylindrical, or lanceoloid; septum margins not expanded basally (not forming sacklike pouch around proximalmost seeds); seeds biseriate.
B. glabella
5. Fruits lanceoloid-subulate; septum margins broadly expanded basally (forming sacklike pouch around proximalmost seeds); seeds somewhat to nearly uniseriate
→ 6
6. Fruit valves pubescent; petals 2.4-3.8(-4) × (0.8-)1-1.3(-2) mm, (claws often not well- differentiated from blades).
B. fernaldii
6. Fruit valves glabrous or sparsely pubescent; petals (3-)3.3-4.8(-5) × (1.2-)1.4-2.5(-3) mm, (claws usually well-differentiated from blades).
B. longii
Source FNA vol. 7, p. 549. FNA vol. 7, p. 546. Author: James G. Harris.
Parent taxa Brassicaceae > tribe Euclidieae > Braya > Braya humilis Brassicaceae > tribe Euclidieae
Sibling taxa
B. humilis subsp. ellesmerensis, B. humilis subsp. maccallae, B. humilis subsp. porsildii
Subordinate taxa
B. fernaldii, B. glabella, B. humilis, B. linearis, B. longii, B. pilosa, B. thorild-wulffii
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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