MUSTARD FAMILY 21 



or not at all saccate but siibcylindric. Petals purple, white, pinkish, or rarely pale 

 yellow, commonly with a narrow undulate or crisped limb and channeled claw, 

 the upper pair sometimes longer (as in no. 21). Stamens tetradynamous, or in 3 

 unequal pairs, the filaments all distinct, or the longer pairs united, or only the 

 upper pair united. Pod narrowly linear, flattened parallel to the partition; valves 

 1-nerved or rarely carinate. Seeds in one row, flat, winged or wingless. — In S. 

 californicus the pods are obcompressed. Species about 35, western North America 

 and Mexico. (Greek streptas, twisted, and anthos, flower, in reference to the 

 petals.) 



Evidence in regard to the validity of the genus Caulanthus. — Of the various species which 

 compose the genus Caulanthus of Watson (Bot. King 27) C. inflatus has been considered a good 

 biological representative. It has been referred to Caulanthus by all authors who have accepted 

 Caulanthus as a genus. It is, however, in every particular of flower structure like various domi- 

 nant types of Californian Streptanthi, such as S. glandulosus Hook. The fruits are essentially 

 similar save that the stigma is 2-lobed in Caulanthus inflatus as opposed to the entire stigma of 

 Streptanthus glandulosus. But other Caulanthus species (such as C. pilosus Wats.) are quite 

 hitermediate in this particular. A study of the sum total of the characters of the most represen- 

 tative or central types of Californian Streptanthi and of the dominant types of Caulanthus 

 indicate, to our mind, that these species are closely derived from one generic type. Phylogenetic 

 considerations point to the arrangement of these forms under one genus name. 



There are other more or less outlying species, study of which lends weight to this judgment. 

 Streptanthus heterophyllus Nutt. is, as a species, very near to Caulanthus coulteri Payson. In 

 this connection Streptanthus insignis Jepson (based on a specimen collected at Waltham, w. 

 Fresno Co., Easttoood, as a type) affords eAddence of value from a genetic standpoint. Its flower 

 characters are to so remarkable a degree those of Streptanthus glandulosus Hook, that not a few 

 careful botanists have distributed specimens of it under this name. The stigma, however, is 

 evidently 2-lobed, rather slightly, to be sure, but still obviously ; while that of S. glandulosus is 

 entire. The latest flowers of the raceme in Streptanthus rasignis are sterile, very congested and 

 black-purple, and so form a terminal color spot. No terminal black spot is found in the racemes 

 of S. glandulosus but it appears again in Caulanthus coulteri. Streptanthus insignis is, in our 

 opinion, rather nearer Caulanthus coulteri than it is to Streptanthus glandulosus. 



Therefore on account of the lack of any real cleavage between Streptanthus and Caulanthus, 

 most species, especially the typical ones, are' here referred to Streptanthus. Such an arrangement 

 as we give below is believed to be more in consonance with the probable phylogeny. ^ 



Certain species require special consideration. For example : Streptanthus longirostris Wats., 

 in our concept of the genera Streptanthus and Thelypodium, goes to the latter genus because of 

 its resemblance to T. lasiophyUum Greene. Like that species or forms of that species, its pods 

 are very slender, more or less rigid, and divaricate-spreading, with the pedicels very short (only 

 about one-half line long). . 



A paper by E. B. Payson entitled "A Monographic Study of Thelypodium and its Allies 

 (Ann. Mo. Bot. Card. 9:233-324,-1922) includes an account of Caulanthus; it is well written, 

 it is vigorous and progressive in treatment, and admirably considered. The author did not, how- 

 ever, include Streptanthus in his investigation. In our judgment Caulanthus and Streptanthus 

 are so close that any decisions fail in effectiveness if either be ignored. 



Bibliog.— Grav, A., On Streptanthus and the plants which have been referred to that genus 

 (Proc. Am. Acad. 6:182-188,-1864). Greene, E. L., Certain West American Crueiferae (Lflts. 

 1:81-90,-1904); Four Streptanthoid genera (Lflts. 1:224-229,-1906). 



A. Stigma 2-lobed; petals plane or somewhat crisped; stem erect, simple or branched; seeds 



mostly wingless, sometimes narrowly winged. 

 Cauline leaves petioled; stamen filaments of equal length, all distinct.— Subgenus Caulanthus. 

 Herbage not glabrous; stem commonly branching, leafy up to the inflorescence; leaves 

 coarsely toothed or pinna tifid. 

 Petals almost included in the calyx; sepals purple; flower buds oblong, glabrous; bien- 



j^g^j .............. 1- ^- P^^osiis. 



Petals distinctly longer than the sepals; sepals pale or whitish; flower buds elliptic- 

 ovate, hispidulose ; annual - ■^- ^>- ««'"*• 



Herbage glabrous; stem naked above the base or bearing a few reduced or bract-like leaves. 



Leaves entire; stem branching; calyx glabrous; perennial 3. A. glaucus. 



Lowest leaves mostly lyrate-pinnatifid. 



Calyx densely white-woolly; stem simple, strongly inflated; annual...... - -•- 



4. o» CTdssicdiitt/St 



Calyx glabrous; stems 1 or several from the base, simple, rarely inflated; perennial. 

 JO) Qg^ major. 



