Sisymbrium Le 
Erect annuel herbs with branching stems which are pubescent with 
simple hairs. Leaves sheowumiagy once pinnatifid or the upper nearly 
antire.e Flowers pale yellow, aispleye® in elongate racemes or panicles. 
Sepals subequal, shade re LineeT » Eee eee 
Styles very short or none. Seeds ina atigis row in each chamber, mareoene: 
Petals 6-8 mme long; pods 6-8 cm. long, spreading Dd. Se altissimum 
Petals 3-3.5 mm. long; pods 1.5 cm. long, erect, 
closely pressed to the stem }. Se officinale 
L. )Seo — 
1. Se officinale Ke 6dge Mustard. Stems 30-100 om. tall or 
more, divaricately branching above; leaves runcinate, 6-12 cm. long, sparingly 
hirsute, the hairs simple; flowers yellowish, 5 mm. in diameter; pods rigid, 
thick-walled, 1.5 cme longegon a short stout stipe, tapering, closely appressed 
¢0 the widely spreading branches of the inflorescence, glabrate. (Erysimun 
" ore Y officinale L.) 
An unsightly/weed of waste places, especially of the grassland. 
2. S- altissimum Le. Tumbling Mustard. Erect, much-branched, rather 
diffuse weed, commonly 1 m. tall, glabrous or sparingly hirsute near the base, ; 
the hairs simple; lower leaves 12-20 cme long, narrowly oblong or oblanceolate, — 
deeply pinnatifid into triangular segments, these more or less simately 
toothed or entire; upper leaves with the lobes greatly narrowed, linear; flowers 
pale yellow, 7-8 mme long, pods rigid, spreading, terete, 8-9 cm. long, 1 m. 
or less in diameter on a stout stipe 8-10 mme long, equal to or greater in 
diameter than the pod itself. 
A common and often abundant weed of the grassland, naturalized fran 
Hurope e 
Arabidopsis thaliana (L,) Heynhold. Annual with the aspect of Sisymbriun, 
the stems slender, 15-40 cm, tall, sparingly pubescent, setulose below; 
leaves small, recalling Capsella, oblanceolate, 2-5 cm. longs petals white; 
pods 4-angled, glabrous, ascending, 1-1.5 cm. long, (Sisymbrium thalianun Gray), 
— Introduced European weed, infrequent, on dry prairies. 
as on 
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