Ig PLANTS WRIGHTIAN*. YI. 



pendula, subcompressa, immarginata. Cotjledones ovales, planse, radiculse adscen- 

 denti subobliqiise accumbentes. — Herba annua vel biennis ; foliis runcinato-pinna- 

 tifidis, vadicalibus pra^sertim pube simplici molliter villosis subpetiolatis ; racerais 

 multifloris, pedicellis etiam fructiferis confeitis ; floribus albis. 



Dryopetalon runcinatum. (Tab. XI.) — On mountains, near Lake Santa Ma- 

 ria, Chihuahua; April: mostly in fruit. (1314.) — Stem one to two feet high, 

 branching, glabrous. Radical leaves 3 or 4 inches long, numerous, in a cluster, 

 short-petioled, oblong or obovate, pubescent or villous, especially beneath, with soft 

 and simple spreading hairs, deeply runcinate-pinnatifid ; the lobes oval or oblong, 

 coarsely toothed. Cauline leaves few, successively smaller and with narrower lobes, 

 but otherwise similar, not auriculate or dilated at the base ; the lower more or less 

 petioled. Racemes one or two, or in fruit sometimes five or seven inches long. Pedi- 

 cels closely approximate even at maturity, in flower ascending and 2 or 3 lines long ; 

 in fruit spreading and 5 or 6 lines long. Petals 3 lines in length, twice the length 

 of the lax sepals, white, narrowly obovate ; the limb incisely pinnatifid into 5 or 

 usually 7 lobes, of which the upper are larger, and the lower very small, all direct- 

 ed forwards. Siliques about an inch and a half long, barely half a line in thick- 

 ness, more or less arcuate-recurved, tipped with a small sessile stigma; the semi- 

 cylindrical valves marked with a rather strong and prominent midnerve, and with a 

 very slender lateral nerve (or at the base more than one) on each side, obscurely 

 veiny. Seeds minute, numerous, about the width of the slender septum. Cotyle- 

 dons plainly accumbent, but with the radicle slightly oblique. — With the foliage 

 and pods of Sisymbrium, the crowded pedicels of Thelypodium, and the seeds of 

 Arabis, but less compressed, this plant is one of the few Cruciferte with lobed petals. 

 In habit, as well as in the accumbent cotyledons, it is widely different from Perrey- 

 mondia. Barn, and Schizopetalon, HooA: Moreover, if we neglect the petals, the 

 terete pods will still exclude it from Arabis. Hence I have considered it the type 

 of a new genus, and have named it from the outline of the petals, which is like 

 that of a common oak-leaf. 



Thelypodium Wrightii, Grai/, PI. Wright, p. 1 ; var. foliis caulinis superioribus 

 laciniato-dcntatis, inferioribus pinnatifidis, segmentis majoribus dentatis. — On 

 mountains at the copper mines. New Mexico ; Aug. (845.) — " Stems 2-5 feet 

 high, much branched. Flowers light purple." — These specimens amply confirm 

 the species, by their divaricate pedicels, short petals, and slender pods ; they have 

 besides deeply pinnatifid or laciniate leaves, only the uppermost and rameal ones 

 being merely denticulate. 



Sisymbrium canescens, Nutt. ; Gray, Gen. lU. 1. t. 64. Valley of Coppermine 

 Creek ; Aug. (846.) — A form with coarsely dissected leaves and rather large flow- 

 ers. Also on the Rio Grande ; in February. 



S. auriculatum, Grai/, PL Wri{/ht. p. 8. Hills between the Limpia and Leona 

 Spring; June. (1315.) 



S. DiFFUsuM, Gray, PI. Wright, p. 8. Mountains at the copper mines. New Mex- 

 ico, at the base of rocky ledges ; Aug. (847.) — Fine flowering specimens, with 

 the (white) petals rather longer than the calyx, but scarcely equalling the style. 



