42 CRUCIFERAE 



greenish, turning purplish; petals yellow, aging dull white with purple center, 

 about I'o times as long as the sepals; pods terete, torulose, especially on upper 

 half, commonly falcate or tortuous, attenuate at apex, glabrous, widely divaricate 

 or more or less detlexed, % to 1 inch long; style 1 to IVi lines long; stigma almost 

 entire; pedicels V2 to 1 line long; seed not winged. 



Desert mesas or washes, 1300 to 7000 feet: Inyo Co. and south through the 

 Mohave Desert to the Colorado Desert. East to Arizona. Apr. 



Note on relationship. — A peculiar species which would rest as well in Streptanthus. The 

 petals usually have a broader claw than lamina with a constriction between them which is a strcp- 

 tanthoid character rather than a thclypodioid one. The upper sepals, in addition, are usually 

 slightly longer than the lower, this irregularity being a streptanthoid character. The calyx has 

 the urccolate shape so often found in Streptanthus. It is, on the whole, a species intermediate 

 between Thelypodium and its nearest generic ally, or it might well be considered a primitive 

 Streptanthus. 



Locs. — Pleasant Caiion, Panamint Range; Lee Well, Nelson Range; Randsburg, Heller 7680; 

 Newberry, Ncivlon 504; Ord Mt., Jcpson 15,501 ; Jimgrey, Jepson 15,563; Stoddard Well, Parish 

 11,797; Hespcria, Newlon 468; Cottonwood Mts., n. of Mecca; Palm Canon, Mt. San Jacinto, 

 Newlon 455 ; Blair Valley, e. San Diego Co., Jepson 8672 ; Wagon Wash near Sentenac Canon, e. 

 San Diego Co., Jepson 12,478. Chloride, Ariz., Jones. 



Refs. — Thelypodium cooperi Wats. Proc. Am. Acad. 12:246 (1877), type loc. near Ft. 

 Mohave, Ariz., J. G. Cooper; Jepson, Man. 414 (1925). Guillenia cooperi Greene, Lflts. 1:228 

 (1906). Caxilanthus cooperi Payson, Ann. Mo. Bot. Gard. 9:293 (1922). 



4. HALIMOLOBUS Tausch. 



Canescent herbs. Leaves entire or more or less dentate or sinuate-dentate, the 

 basal ones petioled, the cauline ones sessile or with a short winged petiole. Petals 

 in ours white, the limb elliptic or obovate, gradually drawn down to a narrow claw 

 about as long. Pod slender, terete, in ours slightly torulose. — Species about 11, 

 North and South America. ( Greek alimos, salt, and lobos, a pod, the habit of these 

 plants thought to recall Alyssum halimif olium Willd. ) 



1. H. diffusiis 0. E. Schulz. Stem diffusely branched, often flexuous above, 

 1 to 2 feet high ; herbage ashy with a fine more or less stellately branching pubes- 

 cence; leaf -blades ovate, sinuate to dentate, 1 to 3^4 inches long, shortly petioled 

 or subsessile; petals white, 2^/2 lines long, slightly exceeding the sepals; the limb 

 roundish-obovate; sepals tomentulose; pods slender or subfiliform, "4 to 5 lines 

 long", spreading or almost divaricate, borne on nearly horizontal pedicels; rib of 

 septum broad. 



Dry washes or granite rocks, 4000 to 7000 feet : Inyo Co. East to western Texas. 

 May-June. 



Tax. note. — This is an anomalous species which rests not well in Sisymbrium. No species 

 with forked pubescence occurs in Thelypodium and yet in habit and in aspect, in the character 

 of its pods and their arrangement, there is much that is suggestive of that genus. "In Westgard 

 Pass it was a rather large brushy plant growing on a steep rocky precipice along the road. I had 

 quite made up my mind that it was a Thelypodium and I still think it looks more like one than 

 it does a Sisymbrium." — F. W. Peirson in litt. 



Locs. — Silver Canon, White Mts., Duran 1509; Westgard Pass, Peirson 7539; Deep Spring 

 Valley, ne. Inyo Co., Purpus 5815; Coso Mts., s. Inyo Co. (Contrib. U. S. Nat. Herb. 4:63). 



Refs. — HALIMOLOBUS DIFFUSUS O. E. Schulz; Engler, Pflzr. 4^°^:288 (1924). Sisymbrium 

 diffusum Gray, PI. Wright. 1:8 (1852), type loc. Limpia Pass, Tex., Wright; Sya. Fl. r:138 

 (1895). 



5. SISYMBRIUM L. 



Erect herbs frequently with pinnatifid or finely dissected leaves, the base not 

 clasping or auriculate. Flowers small (% to 2i/^ lines long), yellow or white. 

 Sepals oblong or linear, equaling or exceeding the claws of the petals. Pod linear 

 or oblong, terete or nearly so, the valves more or less distinctly 3-nerv'ed; stigma 



