4. Rorippa sphaerocarpa (Gray) Britt. 



Annual or biennial; stems 1-3 dm. tall, erect or decumbent, diffusely branched 

 from the base, glabrous; leaves oblong, the lower ones lyrate-pinnatifid to sinuately 

 lobed, the upper ones nearly entire; pedicels 2-3 mm. long, rarely to 5; petals 

 yellow, about 1.5 mm. long; siliques globose or nearly so, typically 2 (rarely 3) 

 mm. in diameter; style about 0.5 mm. long, the stigma not much enlarged. 



In water of streams, marshes, seepage areas, wet meadows and mud about lakes 

 and ponds in N. M. (Catron, Colfax, Sandoval, Taos and Union cos.) and Ariz. 

 (Coconino and Navajo cos.), June-Oct.; 111. to Wyo., s. to N. M., Ariz, and Calif. 



This plant is placed by some authors in R. obtusa, and perhaps rightly so. 

 However, when plants with strictly orbicular fruits are compared with plants of 

 typical R. obtusa with its ovoidish pointed fruits the two look quite different. 



5. Rorippa islandica (Oeder) Borbas. Bog marsh-cress. 



Annual or biennial; stems 2-13 dm. tall, simple or branched above, glabrous 

 to hirsute with simple pointed trichomes; leaves pinnate to pinnatifid or merely 

 toothed; pedicels filiform, 4-12 mm. long, usually about equaling the fruit, spread- 

 ing; sepals about 2 mm. long; petals yellow, 1.7-2 mm. long; stamens 6; siliques 

 slenderly ellipsoid to ovoid, (2-) 3-10 mm. long, 1-4 mm. thick; style 0.5-1 mm. 

 long; seeds plump, cordiform, 0.4—0.9 mm. long. R. palustris (L.) Bess.; R. 

 hispida (Desv.) Britt. 



In marshes, bogs, muddy soil on edge of ponds, seepage areas, about springs 

 and along streams in Okla. (Alfalfa, Caddo, Craig, Custer, Bryan, Grady, Mc- 

 Curtain and Delaware cos.), n.e. and n.w. Tex., N.M. (Lincoln, Otero, Sandoval, 

 San Juan, San Miguel and Taos cos.) and Ariz. (Apache, Coconino, Greenlee and 

 Pinal COS.), May-Sept.; widely distributed throughout much of N.A. and Euras. 



We have several phases of this highly variable species whose separation is 

 adapted from Fernald. 



1. Leaves all or nearly all pinnate to deeply pinnatifid, the numerous lanceolate 

 dentate segments decurrent along the rachis; siliques slenderly 

 ellipsoid, often curved, 4-10 mm. long, equaling the pedicels; thin- 

 leaved glabrous plant var. islandica. 



1. Lower leaves merely pinnatifid to runcinate or uncleft, the middle and upper 



leaves coarsely toothed to subentire: plants relatively coarse, to 13 

 dm. tall, the leaves (except when submersed) firm (2) 



2(1). Siliques slenderly ellipsoid to subcylindric, 3-9 mm. long, 1-2.5 mm. 



thick; plant glabrous throughout or the stem hispid below 



var. Fernaldiana Butt. & Abbe. 



2. Siliques short-ellipsoid to ovoid or subglobose, 2-5.5 mm. long, 1.7-4 mm. 



thick; base of stem or lower leaves frequently hispid 



var. hispida (Desv.) Butt. & Abbe. 



6. Rorippa curvisiliqua (Hook.) Bessey. 



Annual or biennial, diffusely branched or single-stemmed and branched above, 

 1-4 dm. tall, the branches ascending, glabrous to sparsely strigillose throughout 

 or only on the stems; leaves variable, 2-7 cm. long, usually somewhat oblong- 

 lanceolate, nearly entire to toothed or pinnately parted to pinnatifid, the oblong 

 to ovate obtuse segments entire to dentate; flowers in short racemes; pedicels 

 mostly spreading, usually 2-4 mm. long, occasionally more, about half as long as 

 fruit; sepals 1-2 mm. long, promptly deciduous or remaining until the fruits are 

 well-formed; petals yellow, 1-2 mm. long; siliques 8-15 mm. long, 1-1.5 mm. 

 broad, nearly terete, curved or sometimes straight; style 0.3-1 mm. long, the 

 small stigma entire; seeds finely areolate-papillate. 



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