Jones: Flora of Illinois, 71. Cruciferae 139 



5. Barbarea R. Br. — Wintercress 



1. Petals bright yellow, 6-8 mm. long; basal leaves with 2-8 lateral leaflets; 

 mature pods 1.5-2.5 cm. long, the pedicel not as thick as the pod; road- 

 sides, fields, and waste places, very common; nat. from Eur. Apr. -June 

 [B. stncta of auth., not Andrz.; B. barbarea (L.) MacM.} Common 

 Wintercress B. vulgaris R. Br. 



1. Petals pale yellow, 4-6 mm. long; basal leaves with 8-16 lateral leaflets; 

 mature pods 5-6 cm. long; pedicels about as thick as the pods; waste 

 places, occasional; nat. from Eur. May- June. [5. praecox R. Br.] Early 

 Wintercress B. verna (Mill.) Aschers. 



6. RoRiPPA Scop. — Yellow Cress 



(Radicula Hill) 

 1. Petals 3-5 mm. long; perennials with rhizomes. 



2. Leaves pinnately divided, not auriculate at base; pods linear, the style 0.5 



mm. long; moist ground, nat. from Eur. May-Sept 



R. sylvestris (L.) Besser 



2. Leaves pinnately lobed, auriculate at base; mature pods cylindrical, the 



style 2-3 mm. long; river banks. Apr.-Aug 



R. sinuata (Nutt.) Hitchc. 



1. Petals 1.5-2 mm. long; leaves with small auricles at base; style on mature 

 pod not more than 0.5 mm. long; annual or biennial native species. 



3. Mature pods 6-12 mm. long, on pedicels 0.5-2 mm. long; stem glabrous; 



muddy creek banks, common. May-Oct 



R. sessiliflora (Nutt.) Hitchc. 



3. Mature pods 2-5 mm. long, on pedicels 3-10 mm. long. 



4. Stem glabrous or nearly so; wet ground or in water, common. May- 

 Oct R. palustris (L.) Besser 



4. Stem hirsute; wet soil. June-Aug R. Inspida (Desv.) Britt. 



7. Sisymbrium L. 



1. Pods 1-1.5 cm. long, on very short pedicels closely appressed to the stem; 

 petals 3 mm. long; stem divaricately branched above; leaves pinnatifid 

 into 5-13 lobes; waste ground, common, nat. from Eur. May-Sept. Hedge 

 Mustard S. officinale (L.) Scop. 



1. Pods 3-10 cm. long, spreading or ascending on slender pedicels; petals 5-8 

 mm. long. 



2. Lower part of stem spreading-hirsute; upper leaves with linear divisions; 

 petals pale yellow, 6-8 mm. long; pods 7-10 cm. long, the ascending 

 pedicels 5-8 mm. long; a common weed in fields and waste places, nat. 

 from Eur. May-Aug. Tumble Mustard S. altissimum L. 



2. Lower part of the stem retrorsely hirsute; upper leaves with lanceolate 

 divisions; petals bright yellow, 5-6 mm. long; pods 3 cm. long, on 

 spreading pedicels 1-1.5 cm. long; fields and waste places, adv. from 

 Eur S. loeselii L. 



