Descurainia brevisiliqua

(Detling) Al-Shehbaz & Goodson

Harvard Pap. Bot. 12: 421. 2007.

Basionym: Descurainia obtusa subsp. brevisiliqua Detling Amer. Midl. Naturalist 22: 499. 1939
Treatment appears in FNA Volume 7. Treatment on page 521. Mentioned on page 520.

Biennials; eglandular; finely pubescent, often canescent, trichomes dendritic, rarely also mixed with simple ones. Stems erect, unbranched basally, branched distally, 6–11 dm. Basal leaves: petiole 0.5–1.5 cm; blade pinnate, oblanceolate to obovate or ovate in outline, 1–5 cm, lateral lobes (2–5 pairs), linear, margins entire or serrate to incised (apex obtuse). Cauline leaves sessile or shortly petiolate; blade smaller distally, distal lobes often narrower, surfaces densely pubescent. Racemes (paniculate, often with short branches), considerably elongated in fruit. Fruiting pedicels divaricate-ascending, straight, 4–7 (–11) mm. Flowers: sepals spreading, yellowish, oblong, 1.4–2 mm, pubescent, (trichomes dendritic, sometimes mixed with simple ones); petals oblanceolate, 0.7–1 × 0.1–0.2 mm; median filaments 1.5–2 mm; anthers 0.2–0.3 mm. Fruits divaricate to erect, linear to oblong, not torulose, 3–8 (–10) × 1–1.2 mm; valves each with distinct midvein; septum not veined; ovules 10–28 per ovary; style obsolete to 0.1 mm, glabrous. Seeds biseriate, light-brown, ellipsoid, 0.5–0.7 × 0.3–0.4 mm. 2n = 42.


Phenology: Flowering (late Jun-)Jul–Aug(-early Oct).
Habitat: Pine and juniper communities, rocky washes, roadsides, grasslands, gravelly mesa
Elevation: 1900-2500 m

Discussion

R. C. Rollins (1993) reduced Descurainia brevisiliqua to synonymy of the diploid D. obtusa. This hexaploid species differs from the latter in having biseriate (versus uniseriate) seeds and glabrous (versus densely to moderately pubescent) fruits. Molecular data (B. E. Goodson 2007) show that it is consistently separate from, and unrelated to, D. obtusa, instead being affiliated with D. incana and D. incisa. Descurainia brevisiliqua differs from the latter two species by having biseriate (versus uniseriate) seeds and oblong, non-torulose fruits that, unlike those of D. incana, are not appressed to rachises. Although the fruits of D. brevisiliqua resemble those of some D. pinnata subspecies, it can be readily distinguished from the latter by its tall, strict growth habit with numerous short branches in the distal part of the plant, more linear leaf segments, stems that are usually purple, and late–summer flowering period.

Selected References

None.

Lower Taxa

None.

"elongated" is not a number."thick" is not a number."dm" is not declared as a valid unit of measurement for this property.

... more about "Descurainia brevisiliqua"
oblong +  and ovate +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
Barbara E. Goodson +  and Ihsan A. Al-Shehbaz +
(Detling) Al-Shehbaz & Goodson +
Descurainia obtusa subsp. brevisiliqua +
appendaged +  and unappendaged +
not auriculate +
dissected +, repand +, sinuate +, crenate +  and dentate +
oblanceolate;obovate or ovate +
smaller +
1 cm10 mm <br />0.01 m <br /> (5 cm50 mm <br />0.05 m <br />) +
urceolate +, campanulate +  and tubular +
branched +  and simple +
petiolate +  and sessile +
well-developed +
distinct +
not +  and differentiated +
emarginate +  and entire +
Ariz. +, N.Mex. +  and Tex. +
1900-2500 m +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
actinomorphic +
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
not torulose +, linear +  and oblong +
0.1 cm1 mm <br />0.001 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
Pine and juniper communities, rocky washes, roadsides, grasslands, gravelly mesa +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
serrate to incised +  and entire +
toothed;entire +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
white +  and yellow +
0.7mm;1mm +
rudimentary +
oblanceolate +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Flowering (late Jun-)Jul–Aug(-early Oct). +
trinucleate +  and 3(-11)-colpate +
Harvard Pap. Bot. +
bracteate;ebracteate +
0.7 cm7 mm <br />0.007 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
divaricate-ascending +
slender +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
mucilaginous +
not +  and mucilaginous +
light-brown +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
ellipsoid +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
persistent +  and caducous +
distinct +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
reduced +
terete +, torulose +, obovoid +, ellipsoid +, fusiform +, clavate +, oblong +  and linear +
terete +, torulose +, obovoid +, ellipsoid +, fusiform +, clavate +, oblong +  and linear +
tetradynamous +
branched +  and unbranched +
procumbent +  and decumbent +
2-lobed +, entire +, conical +  and capitate +
subsessile +, sessile +  and petiolate +
persistent +
distinct +
0 cm0 mm <br />0 m <br /> (0.01 cm0.1 mm <br />1.0e-4 m <br />) +
Huguenenia +  and Sophia +
Descurainia brevisiliqua +
Descurainia +
species +
coiled +, 1-7-veined +  and veined +
pubescent +  and glabrous +
anastomosing +
canescent +  and pubescent +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +