FLOWERING PLANTS AND FERNS OF ARIZONA 353 



5. Brassica juncea (L.) Cosson, Soc. Bot. France Bui. 6: 609. 1859. 



Sinapis juncea L., Sp. PL 668. 1753. 



Flagstaff (Coconino County). Prescott (Yavapai County). Widely 

 distributed in the United States; introduced from Asia. 

 Indian mustard. 



The garden radish, Raphanus sativus L. and wild radish, R. raphanistrum L., 

 are likely to be found in waste places in Arizona. They are easily distinguished 

 from Brassica by their indehiscent pods with spongy cross partitions between 

 the seeds, the garden radish also by its white or pink petals. 



17. BARBAREA. Wixtercress 



Plants commonly biennial, glabrous; stems erect, branched above, 

 angled; leaves lyrate-pinnatifid; flowers in elongate racemes, the petals 

 yellow; pods elongate, 4-sided; seeds in 1 row in each cell. 



1. Barbarea orthoceras Ledeb., Hort. Dorp. 1824; Fl. Ross. 1: 114. 



1841. 



Labrador to Alaska, south to Xew Hampshire, Colorado, Arizona, 

 California, and Mexico, also in Eurasia, flowering in spring and early 

 summer. 



The typical form of the species, with pods appressed or strongly 

 ascending and rather crowded, has been collected at Buck Springs, 

 Coconino County (Collom 778), and in the Chiricahua Mountains, 

 Cochise County (Blumer in 1907). A western form, var. dolichocarpa 

 Fernald, with pods spreading or ascending and not crowded, occurs 

 near Flagstaff (MacDougal 24, Peebles and Smith 13605). 



18. DRYOPETALOX 



Plant annual; stems branching above, hispid below; leaves sharply 

 incised with retrorse teeth or lobes; flowers in crowded racemes; 

 sepals strongly gibbous at base; petals bright white, with pinnately 5- 

 to 7-cleft blades; pods long and slender, terete, spreading or somewhat 

 recurved. 



1. Dryopetalon runcinatum A. Gray, PI. Wright. 2: 12. 1853. 



Greenlee, Gila, Pinal, Santa Cruz, and Pima Counties, 2.000 to 

 4.000 feet, commonly in moist rock creviees in canyons, February to 

 May. Xew Mexico and southern Arizona, probably also northern 

 Mexico. 



19. RORIPPA 



Plants annual or perennial; stems usually branched; leaves simple 

 or pinnate; flowers in racemes, these rather short and dense at first, 

 becoming loose and elongate; petals yellow or white; pods globose to 

 elongate and narrowly cylindric; seeds commonly in 2 rows, very 

 small, turgid. 



The plants all prefer wet ground and one species, the true water- 

 cress (R. nasturtium-aquaticum) , is semiaquatic. 



