Draba CRUCIFER.E. 27 



25. Fhysaria. Pod diJymous ; cells nearly globular. Stellate-canescent perennials, with entire 



leaves. 



II. Pod of 2 indehiscent cells, separating at maturity from the persistent axis. 



26. Senebiera. Cells small, globose, rugose or tuberculate. Seed turgid ; cotyledons incum- 



bent. Flowers white, minute, in racemes opposite to the pinnatifid leaves. 



27. Biscutella. Cells flat, nearly orbicular. Seeds flat. Flowers rather large. Stigma dilated 



or conical, nearly sessile. 



III. Pod indehiscent, 1-celled or transversely jointed. 



28. Thysanocarpus. Tod small, plano-convex, orbicular, winged or margined, 1-seeded. 



Slender annuals. 



29. Raphauus. Pod elongated, terete or necklace-form, attenuated above, several-seeded. 



Coarse introduced annuals or biennials. 



1. PLATYSPERMUM, Hook. 



Pod orbicular, flat, with flat nerveless valves and hyaline partition. Seeds few, 

 orbicular, flat and broadly margined with a thin wing ; cotyledons accumbent. 

 Sepals equal, spreading. Petals obovate, scarcely clawed. — A low delicate annual ; 

 with radical simple or pinnatifid leaves, and several slender 1-flowered scapes ; 

 flowers small, white. 



1. P. scapigerum, Hook. Glabrous: leaves usually runcinately pinnatifid: 

 scapes 2 to 3 inches high : flowers erect or nodding : pod 8- 12-seeded. — PL i. 68, 

 t. 18. 



Ou dry hillsides in the shade of larger plants, in early spring ; of short duration. Sierra Co. 

 (Lcmmon) ; Steamboat Springs, Xevada (fixation) ; and northward to the Columbia. 



2. ALYSSUM, Tourn. 



Pod oval or orbicular, compressed ; valves convex and nerveless. Seeds 1 or 2 



in each cell ; cotyledons accumbent. Sepals equal. Petals white or yellow. 



Longer filaments often toothed. — Low herbs, stellate-canescent, mostly with simple 



leaves. 



A large genus of the Eastern Continent, a few of its species widely naturalized weeds or readily 

 escaping from cultivation. 



1. A. calycinum, Linn. Annual, branching from the root, the stems mostly 

 simple, decumbent at base, i to 1 foot high : leaves entire, linear-spatulate, 6 to 12 

 lines long : flowers small, in slender racemes, the white or pale yellow petals bat 

 little exceeding the short sepals : pods orbicular, with a thin margin, slightly emar- 

 ginate above, li lines in diameter, a little exceeding the persistent sepals, pubescent, 

 I seeded, on spreading pedicels a line lung : .style half a line long. 



A native (if Southern Europe, sparingly naturalized about the Bay of San Francisco. 



2. A. maritimum, Linn. Perennial, somewhat eaneseent with appressed silky 

 hairs, the numerous .stems branching, a fend high or less, ascending or decumbent : 

 leaves lanceolate spatulate, entire : flowers 2 lines long, the broad white petals twice 

 longer than the deciduous sepals: pod orbicular, a line broad, nearly smooth, 

 pointed with the slender style, 2-seeded : pedicels slender, 3 to t lines long, spread- 

 ing horizontally. 



< Iften cultivated for its fragrant flowers under the name of Sweet Ahjssum. Native about the 



Med iteir.iiir.ii i ; spaiingly natural i/rd mar Oakland. 



3. DRABA, Linn. 



Pod oval to oblong or linear, flat ; valves nearly tl it. nerveless or faintly 1 -nerved. 

 Seeds few to many, in 2 rows in each cell, wingless ; cotyledons accumbent Sepals 



