Descurainia incisa

(Engelmann ex A. Gray) Britton

Mem. Torrey Bot. Club 5: 173. 1894.

Basionym: Sisymbrium incisum Engelmann ex A. Gray Mem. Amer. Acad. Arts, n. s. 4: 8. 1849
Treatment appears in FNA Volume 7. Treatment on page 523. Mentioned on page 519, 520, 521.

Annuals; glandular or eglandular; densely to sparsely pubescent, glabrous or pubescent distally, sometimes canescent, trichomes dendritic. Stems erect, usually unbranched basally, branched distally or sometimes throughout, (1.3–) 2–8.2 (–10.7) dm. Basal leaves: petiole 0.5–4.7 cm; blade pinnate, obovate to oblanceolate in outline, 1.5–10.3 cm, lateral lobes (2–9 pairs), ovate or oblong to lanceolate or linear, margins usually dentate to incised or entire, rarely pinnatifid or crenate. Cauline leaves sessile or shortly petiolate; blade smaller distally, distal lobes oblong, lanceolate, linear, (margins dentate to denticulate or entire), surfaces pubescent or glabrous. Racemes considerably elongated in fruit, (glandular or eglandular). Fruiting pedicels ascending to divaricate or horizontal, straight, (3–) 5–25 (–30) mm. Flowers: sepals erect to ascending, yellowish, oblong to ovate, 1.6–2.4 mm, glabrous or pubescent; petals narrowly oblanceolate, 1.7–2.8 × 0.5–0.9 mm; median filaments 1.6–2.4 mm; anthers 0.3–0.4 mm. Fruits erect to ascending, linear, slightly torulose, 8–20 × 0.9–1.3 mm, (straight or slightly to strongly curved inward); valves each not veined or with distinct midvein; septum not veined; ovules 14–26 per ovary; style 0.1–0.3 mm, glabrous. Seeds uniseriate, reddish-brown, oblong, 0.9–1.3 × 0.5–0.6 mm.

Distribution

V7 822-distribution-map.gif

Alta., B.C., Yukon, Ariz., Calif., Colo., Idaho, Mont., N.Mex., Nev., Oreg., Utah, Wash., Wyo., n Mexico

Discussion

Subspecies 2 (2 in the flora).

As delimited by various authors and as represented in all major herbaria consulted, Descurainia incisa is highly variable in almost all features. The variation is most likely the result of hybridization with all species of the genus that have overlapping ranges. Forms with few-seeded, short fruits tapering at both ends most likely represent hybrids with D. californica; those with sub-biseriate seeds most likely resulted from crossing with D. pinnata, and the origin of forms with somewhat subappressed fruits almost certainly involved D. incana. The recognition of glandular versus eglandular forms as distinct varieties or subspecies is completely artificial. The lectotype (Fendler 29, GH) and isolectotype (MO) are eglandular; a syntype (Fendler 31, MO) is densely glandular.

Selected References

None.

Key

1 Fruiting pedicels ascending to divaricate, (3-) 5-10(-12) mm; lateral lobes of basal and proximal cauline blades (3-)5-9 pairs, margins usually coarsely dentate to incised, rarely crenate or pinnatifid; lobes of distal cauline blades oblong to lanceolate, margins dentate to denticulate; fruits straight or curved inward. Descurainia incisa subsp. incisa
1 Fruiting pedicels horizontal to divaricate, (10-) 13-25(-30) mm; lateral lobes of basal and proximal cauline blades 2 or 3 (or 4) pairs, margins usually entire; lobes of distal cauline blades linear, margins entire; fruits curved inward. Descurainia incisa subsp. paysonii

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

... more about "Descurainia incisa"
oblong +  and ovate +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
Barbara E. Goodson +  and Ihsan A. Al-Shehbaz +
(Engelmann ex A. Gray) Britton +
Sisymbrium incisum +
appendaged +  and unappendaged +
not auriculate +
dissected +, repand +, sinuate +, crenate +  and dentate +
obovate;oblanceolate +
smaller +
1.5 cm15 mm <br />0.015 m <br /> (10.3 cm103 mm <br />0.103 m <br />) +
urceolate +, campanulate +  and tubular +
branched +  and simple +
petiolate +  and sessile +
well-developed +
distinct +
not +  and differentiated +
emarginate +  and entire +
lanceolate +  and oblong +
Alta. +, B.C. +, Yukon +, Ariz. +, Calif. +, Colo. +, Idaho +, Mont. +, N.Mex. +, Nev. +, Oreg. +, Utah +, Wash. +, Wyo. +  and n Mexico +
straight +  and curved +
not winged +  and unappendaged +
connate +  and distinct +
actinomorphic +
0.8 cm8 mm <br />0.008 m <br /> (2 cm20 mm <br />0.02 m <br />) +
erect +  and ascending +
torulose +
0.09 cm0.9 mm <br />9.0e-4 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
oblong;lanceolate or linear +
sessile +  and petiolate +
alternate +, not +  and rosulate +
cauline +  and basal +
connate +  and distinct +
decurrent +
entire +, dentate +  and pinnatisect +
usually dentate;incised or entire rarely pinnatifid or crenate +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.24 cm2.4 mm <br />0.0024 m <br />) +
tenuinucellate +, crassinucellate +  and bitegmic +
campylotropous +  and anatropous +
white +  and yellow +
1.7mm;2.8mm +
rudimentary +
oblanceolate +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (4.7 cm47 mm <br />0.047 m <br />) +
trinucleate +  and 3(-11)-colpate +
Mem. Torrey Bot. Club +
bracteate;ebracteate +
2.5 cm25 mm <br />0.025 m <br /> (3 cm30 mm <br />0.03 m <br />) +
horizontal +  and ascending +
slender +
0.5 cm5 mm <br />0.005 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
mucilaginous +
biseriate +  and uniseriate +
not +  and mucilaginous +
reddish-brown +
0.09 cm0.9 mm <br />9.0e-4 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
persistent +  and caducous +
distinct +
erect +  and ascending +
pubescent +  and glabrous +
oblong +  and ovate +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.24 cm2.4 mm <br />0.0024 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 +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
glabrous +  and pubescent +
Huguenenia +  and Sophia +
Descurainia incisa +
Descurainia +
species +
with distinct midvein +  and not veined +
pubescent +  and glabrous +
anastomosing +
eglandular +  and glandular +
canescent +, pubescent +  and glabrous +
rhizomatous +, taprooted +, scapose +  and not +
perennial +, biennial +  and annual +
subshrub +  and herb +
aquatics +  and terrestrial +
glabrous +  and pubescent +