Rapistrum rugosum
Rapistrum
annual bastard-cabbage, bastard-cabbage, common giant mustard, turnipweed, wild rape, wild turnip
bastardcabbage, turnip, turnipweed, wild-turnip
(1–)2–10(–15) dm.
erect, unbranched or branched basally.
basal and cauline; petiolate or subsessile;
basal not rosulate, petiolate, blade margins usually pinnate to lyrately pinnatifid, rarely undivided, dentate;
cauline subsessile or shortly petiolate, blade (base not auriculate), margins lobed, subentire, or dentate.
petiole 1–5 cm;
blade with 1–5 lobes each side, 2–25 cm, margins irregularly dentate, lateral lobe oblong or ovate, terminal lobe suborbicular or ovate, larger than lateral.
blade simple or sinuately lobed, margins subentire or dentate.
(corymbose, several-flowered), greatly elongated in fruit.
sepals 2.5–5 mm;
petals pale yellow, 6–11 × 2.5–4 mm;
filaments 4–7 mm;
anthers 1.2–1.5 mm.
sepals ascending, oblong, lateral pair not saccate basally, (hispid [glabrous or with subapical tuft of hairs]);
petals yellow, obovate, claw differentiated from blade, (apex ± truncate);
stamens tetradynamous;
filaments not dilated basally;
anthers ovate to suboblong, (apex obtuse);
nectar glands confluent, median glands present.
erect, (appressed to rachis), 1.5–5 mm.
erect [ascending], (usually appressed to rachis), slender to stout.
valvular segment ellipsoid, 0.7–3 × 0.5–1.5 mm;
terminal segment globose or ovoid, 1.5–3.5 × 1–2.8 mm, usually rugose or ribbed, rarely smooth;
style 1–3(–5) mm.
silicles, indehiscent, sessile, segments 2, elliptic to oblong, torulose, (slightly to strongly constricted at transverse joint), terete or angular; (valvular segment persistent, dehiscent [indehiscent], 1(–3)-seeded, longitudinally striate or smooth, occasionally seedless and nearly as wide as pedicel;
terminal segment indehiscent, caducous at maturity, usually 1-seeded, rarely seedless);
valves glabrous or pubescent;
septum complete;
ovules 2–4; (style persistent, filiform);
stigma capitate, (flattened), 2-lobed.
1.5–2.5 mm.
uniseriate, slightly compressed, not winged, ovoid [oblong];
seed coat (smooth), not mucilaginous when wetted;
cotyledons conduplicate.
= 8.
= 16.
Rapistrum rugosum
Rapistrum
Three subspecies of Rapistrum rugosum have been recognized, including: subsp. rugosum, subsp. linnaeanum Rouy & Foucaud, and subsp. orientale (Linnaeus) Arcangeli. They are distinguished mainly on the basis of silique shape, rugosity, prominence of ribs, and the length and thickness of fruiting pedicels. These features vary considerably and intergradation occurs in such a wide array of combinations that it seems rather meaningless to recognize them without further studies. All three subspecies and some of their intermediates have been found in the United States (I. A. Al-Shehbaz 1985; R. C. Rollins 1993). The species was first collected in the flora area in 1873 as a ballast plant from Boston, Massachusetts (Al-Shehbaz).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 2 (1 in the flora).
Both species of Rapistrum have been introduced into North America; only R. rugosum has persisted with naturalized populations. Rapistrum perenne (Linnaeus) Allioni was first collected in 1922 from southeastern Saskatchewan but has not been seen or collected from there since 1932. It can be distinguished by being a perennial with a conical style shorter than the strongly 8-ribbed terminal segment, whereas R. rugosum is an annual with a slender, filiform style longer than the slightly ribbed terminal segment.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
LA Plants, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
