Descurainia pinnata subsp. brachycarpa

(Richardson) Detling

Amer. Midl. Naturalist 22: 509. 1939.

Endemic
Basionym: Sisymbrium brachycarpum Richardson in J. Franklin et al., Narr. Journey Polar Sea, 744. 1823 (as brachycarpon)
Synonyms: Descurainia intermedia (Rydberg) Daniels Descurainia magna (Rydberg) F. C. Gates Descurainia pinnata var. brachycarpa (Richardson) Fernald Descurainia pinnata subsp. intermedia (Rydberg) Detling Descurainia pinnata var. intermedia (Rydberg) C. L. Hitchcock Descurainia ramosissima Nuttall Hesperis brachycarpa (Rydberg) Garrett Sisymbrium brachycarpum var. intermedium (Rydberg) J. F. Macbride Sisymbrium canescens var. brachycarpum (Richardson) S. Watson Sisymbrium intermedium (Richardson) Rydberg Sisymbrium multifidum subsp. brachycarpum (Richardson) Thellung Sisymbrium pinnatum var. brachycarpum (Richardson) Jepson Sophia brachycarpa (Walter) Howell Sophia intermedia Sophia magna Sophia pinnata var. brachycarpa (Richardson) Farwell
Treatment appears in FNA Volume 7. Treatment on page 527. Mentioned on page 525, 528.

Plants usually glandular, rarely eglandular, usually not canescent. Stems unbranched basally, branched distally. Racemes: rachis sparsely to densely pubescent, often glandular. Fruiting pedicels divaricate to ascending, forming 20–60(–80)º angle, (7–)10–18(–23) mm. Flowers: sepals yellow, 1.5–2.6 mm; petals (1.7–)2–3 × 0.6–1 mm. 2n = 14, 28.


Phenology: Flowering Mar–Jul.
Habitat: Roadsides, sagebrush and pinyon-juniper communities, disturbed sites, sandy fields, dry washes, limestone ledges, foothills, canyon margins, gravel washes, dry slopes, cliffs, streamsides, railroad tracks and embankments, prairies, sandy grounds
Elevation: 100-2100 m

Distribution

V7 832-distribution-map.gif

Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Ark., Calif., Colo., Idaho, Ill., Ind., Iowa, Kans., Ky., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.Y., N.Dak., Ohio, Okla., Oreg., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., Wis., Wyo.

Discussion

Except for having numerous instead of one or few stems from the base, Descurainia ramosissima is indistinguishable from D. pinnata subsp. brachycarpa in every aspect of indumentum, leaf morphology, flower size, seed size and arrangement, and fruit size and orientation. Plants of the type collections (Rollins et al. 8349, holotype GH, isotypes GH, MO) are infected with white rust, a fungus disease rarely encountered elsewhere in North American Descurainia. It is not known if this unusual branching is inherited or disease-related, but it should not be used as the main reason for recognizing a species separate from D. brachycarpa.

Although subsp. brachycarpa is almost always glandular in the inflorescence, both glandular and eglandular forms are found in some populations. Cases in point are J. & H. Massey 1931 and Dunn 2 (both at TEX) that were collected from Cleveland and Caddo counties, Oklahoma, respectively.

Selected References

None.

Lower Taxa

None.
Barbara E. Goodson +  and Ihsan A. Al-Shehbaz +
(Richardson) Detling +
Sisymbrium brachycarpum +
Alta. +, B.C. +, Man. +, N.W.T. +, Nunavut +, Ont. +, Que. +, Sask. +, Ark. +, Calif. +, Colo. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, Mich. +, Minn. +, Mo. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.Y. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Vt. +, Va. +, Wash. +, Wis. +  and Wyo. +
100-2100 m +
Roadsides, sagebrush and pinyon-juniper communities, disturbed sites, sandy fields, dry washes, limestone ledges, foothills, canyon margins, gravel washes, dry slopes, cliffs, streamsides, railroad tracks and embankments, prairies, sandy grounds +
Flowering Mar–Jul. +
Amer. Midl. Naturalist +
Descurainia intermedia +, Descurainia magna +, Descurainia pinnata var. brachycarpa +, Descurainia pinnata subsp. intermedia +, Descurainia pinnata var. intermedia +, Descurainia ramosissima +, Hesperis brachycarpa +, Sisymbrium brachycarpum var. intermedium +, Sisymbrium canescens var. brachycarpum +, Sisymbrium intermedium +, Sisymbrium multifidum subsp. brachycarpum +, Sisymbrium pinnatum var. brachycarpum +, Sophia brachycarpa +, Sophia intermedia +, Sophia magna +  and Sophia pinnata var. brachycarpa +
Descurainia pinnata subsp. brachycarpa +
Descurainia pinnata +
subspecies +