o6 Spring Flora of Ohio. 



Dra-ba ver'-na L. Whitlow Grass. — Leaves all radical, oblong or 

 lanceolate ; scapes 1-."! in. high, petals 2-cIeft. 



10. Genns DES-CU-RAI'-NI-A.— Pods oblong, club-shaped, or ob- 

 long-linear, shorter than the mostly horizontal pedicels; seeds 2- 

 ranked in each cell; leaves 2-pinnatifid, often hoary or downy, the di- 

 visions small and toothed. 



Des-cu-rai'-ni-a pin-na'-ta (Walt.) Britt. {SisymbriiDU canescens 

 Nutt.) Tansy Mustard. — Not common. 



11. Genus STEN-O-PHRAG'-MA.— Pods linear, somewhat 4-sided,, 

 longer than the slender spreading pedicels; leaves obovate or oblong ;^ 

 plant slender, branched. 



Sten-o-phrag'-ma tha-li-a'-na (L.) Celak. {Sisymbrium thaliana 

 Gaud.) Mouse-ear Cress. — Introduced from Europe; not common. 



12. Genus AR'-A-BIS. — Pod linear, flattened, the valves more or 

 less 1-nerved in the middle, or longitudinally veiny; flowers white or 

 purple. 



A. Seeds in one row in each cell, orbicular or nearly so ; plants diffuse or erect.. 

 b. Low, diffuse or spreading from the base^ 



Ar'-a-bis vir-gin'-i-ca (L.) Trel. [A. liidoviciana Meyer.) Rock 

 Cress. — Leaves pinnatel)- parted into oblong or linear few-toothed or 

 entire divisions; flowers small, white; pods rather broadly linear,, 

 spreading, flat. Southern Ohio. 



b. Stems erect, simple, leafy ; pods erect or ascending. 



Ar'-a-bis pa'-tens Sulliv. Rock-cress. — Downy with spreading hairs,, 

 erect, 1-2 ft. high; stem-leaves oblong, ovate, partly clasping by the 

 cordate base; petals white, 4 lines long, twice the length of the calyx ^ 

 pedicels slender, spreading. 



Ar'-a-bis hir-su -ta iL.) Scop. Rock-cress. — Rough-hairy, sometimes 

 smoothish, 1-2 ft. high; stem-leaves oblong or lanceolate, clasping by 

 an arrow-shaped or cordate base; petals greenish-white, small, but. 

 longer than the calyx; pedicels and pods strictly upright. 



b. .'^tenis erect, simple, leafy ; pods recurved, spreading or pendulous.) 



Ar'-a-bis laev-i-ga'-ta (Muhl.) Poir. Rock-cress. — Smooth and glau- 

 cous; stem-leaves partly clasping by the arrow-shaped base, lanceolate 

 or linear ; pods long and narrow, recurved-spreading. 



