138 American Midland Naturalist Monograph No. 2 



24. Pubescence of forked or stellate hairs, at least on the stem. 



29. Petals deeply bifid; pods ellipsoid to nearly globose, scarcely flattened; 

 seeds several in each locule, winged 22. Derteroa 



29. Petals entire or nearly so; pods strongly flattened. 



30. Plants densely stellate-pubescent; pods orbicular, 3 mm. broad, shallowly 



notched at the apex 21. Alvssum 



30. Plants nearly glabrous; pods triangular 29. Capsella 



1. Cakile Ludw. — Sea Rocket 



C. edentula (Bigel.) Hook. Shore of L. Michigan, not common. July- 

 Sept. 



2. Raphanus L. — Radish 



1. Pods conspicuously torulose and longitudinally ridged when dry, 3-4 mm. 

 thick; petals yellowish, spatulate, clawed, veiny, fading whitish or purplish; 

 fields and waste ground, nat. from Eur. June-Aug. [^Raphanistrum inocuum 

 Moench] Wild Radish R. raphanistrum L. 



l.Pods smooth, not torulose, 5-9 mm. thick; petals purple, less commonly 

 white, 1.5-2 cm. long, conspicuously veined; fields and waste ground, 

 escaped from cult. May-Sept. Radish R. sativus L. 



3. Brassica L. 

 1 . Leaves not clasping the stem. 



2. Pods hispid, 3 cm. long, with a flattened beak half the length of the pod; 



fields and waste places, nat. from Eur. Apr.-Aug. White Mustard 



B. alba (L.) Rabenh. 



2. Pods glabrous. 



3. Pods ascending, 3-5 cm. long, 2-3 mm. thick, the beak 4-8 mm. long; 



pedicels ascending, 6-10 mm. long. 



4. Flowering pedicels 3-6 mm. long, shorter than the flowers; beak of 



the pod more or less flattened, usually containing a seed in the 



basal part; fields and waste places, nat. from Eur. May-Sept. Field 



Mustard B. arvensis (L.) Rabenh. 



4. Flowering pedicels 7-10 mm. long, equalling or exceeding the flowers; 

 beak of the pod terete, seedless; fields and waste places, nat. from 

 Eurasia. July-Sept. Indian Mustard B. juncea (L.) Cosson 



3. Pods 'erect, 1-1.5 cm. long, 1-1.5 mm. thick; beak terete, 1.5-2 mm. 

 long; pedicels erect, 3-5 mm. long; lielcb and waste places, nat. from 



Eur. Apr.-Sept. Black Mustard B. nigra (L.) Koch 



1. Upper leaves sessile and claspmg by the auriculate base. 



5. Leaves glaucous; petals pale yellow; fields and waste places, nat. from 



Eur. Apr.-Oct. Yellow Mustard B. campestris L. 



5. Leaves not glaucous; petals bright yellow; waste places, escaped from 

 cult., native of Eur. Turnip B. rapa L. 



4. Diplotaxis DC. 



D. muralis (L.) DC. Sand Rocket. Waste places, occasional, adv. from 

 Eur. June-Aug. 



