Flora of North America species comparison

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Rapistrum rugosum

annual bastard-cabbage, bastard-cabbage, common giant mustard, turnipweed, wild rape, wild turnip
Habit Plants hispid proximally, glabrous distally.
Stems

(1–)2–10(–15) dm.
Basal leaves

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.
Cauline leaves

blade simple or sinuately lobed, margins subentire or dentate.
Flowers

sepals 2.5–5 mm;

petals pale yellow, 6–11 × 2.5–4 mm;

filaments 4–7 mm;

anthers 1.2–1.5 mm.
Fruiting pedicels

erect, (appressed to rachis), 1.5–5 mm.
Fruits

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.
Seeds

1.5–2.5 mm.
2n

= 16.

Rapistrum rugosum
Phenology Flowering Apr–Jul (Nov–Jun in Texas).
Habitat Roadsides, disturbed sites, waste places, fields, grassy banks, ballast
Elevation 0-2000 m [0-6600 ft]
Distribution
from FNA
CA; IN; LA; MA; NJ; NV; NY; OR; PA; TN; TX; WA; WI; ON; QC; Europe [Introduced in North America; introduced also in Mexico, South America, Asia, Africa, Atlantic Islands, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)
Source FNA vol. 7, p. 441. Treatment author: Suzanne I. Warwick.
Parent taxa Brassicaceae > tribe Brassiceae > Rapistrum
Synonyms Myagrum rugosum, R. hispanicum
Name authority (Linnaeus) Allioni: Fl. Pedem. 1: 640. (1785)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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