jgg XIII. CRUCIFERiE. Arabis. 



1 T. GLABRA. Svwoth Toifcr Mustard. 



St erect- radical lis. petiolate. dentate, AVith ramose hairs, caiihne ones 

 broad-lanceolate, sagittate, hali-clasping, glaucous, smooth ; 5iZig^s erect.— 

 Shores of Lake' Superior W. to the Rocky Mts. Natura zed about New 

 B^Tcl Eaton. Stem round, simple, Uf high. Leaves 1-2' long. Siliques 

 2— 3'' long, very narrow. Flowers pale sulphui-yellow. May. 



/? 1 T & G Lis all linear-lanceolate and glabrous, radical ones remotely 

 repand-denticulate, caulim entire.-Watertown, N. Y., on rocks. Torrey i$^ Gray. 



2. T. BRACHYCARPA. TorT. & Gray. 



Glabrous and glaucous ; radical lis. spatulate, dentate, cauline ones linear- 

 lanceolate, sagittate and subamplexicaul ; sillqucs sY^ovi, linear-oblong ;je^t^^ 

 pendulous in flower, spreading in fruit.-® Lake shores, Mich. Stem l-2f 

 high, often purplish, as well as the foliage. Flowers rather large, pale purple. 

 Siliques 1' long, spreading. 



15. arAbis. 



Said to derive its name from Arabia, iU native country. 



Sepals erect ; petals unguiculate, entire ; silique linear, compressed ; 

 valves 1 -veined in the middle; seeds in a single row in each cell. — 

 Fls. white. 



1 A Canadensis. (A. falcata. 3Iichx.) Sickle Pod. 

 Cauline lis. sessile, oblong-lanceolate, narrow at base, pubescent ; pedv- 

 ccls pubescent, reflexed in the fruit ; sUique subfalcate, veined, pendulous ; sds. 

 wan-ed —% On rockv hills. Can. to Ga. W. to Ark. A plant remarkable for 

 its lon^' drooping pods, which resemble a sickle blade, or rather a curved 

 sword blade. Stem 2— 3f high, slender, round, smooth. Leaves 1—3' long, i 

 as wide • the lowest early marescent, middle and upper ones sessile or clasping, 

 wath narrow bases, remotely denticulate. Flow^ers small, white. Pods slen- 

 der, flattened, nearly 3' long. Jn. 



2. A. LTRATA. (Sisymbrium arabidoides. Darl.) 



St and iipper lis. smooth and glaucous ; radical lis. hTately pinnatifid, 

 often pilose ; st. branched at base ; pedicels spreading ; siliques erect.— (§) On 

 rocky hills Can. to Va. Stems often many, united at base, 6—12' high. Root- 

 leaves numerous, rosulate, 1—3' long, i as w^ide, petiolate, lower stem-leaves 

 pinnatifid or sinuate-dentate, upper ones sublinear and subentire. Flowers 

 middle size. Siliques w^hen mature U— 2' long, less than 1" wide. Apr. May. 



3. A. L.EYIGATA. DC. (Turritis laevigata. Muhl.) 



Smooth and glaucous ; radical lis. obovate and oblong, tapering to a pe- 

 tiole dentate, stem lis. linear-lanceolate, amplexicaul, obtuse, nppcr ones entire \ 

 pedicels about as long as the calvx, erect ; siliques very long, linear, at length 

 spreading and pendulous; sds. winged.— Oj. In rocky woods and low grounds, 

 Can to Ark. Stem 1— 2f high, round, smooth, simple or branched above. 

 Root-leaves often purplish, f— U' long, ^ as wide, with acute teeth. Stem- 

 leaves 2 — 5' long, i as wide, upper ones entire. Flow^ers in long racemes. 

 Siliques 2—3' long, ''scarcely 1" wide. May. 



4. A. HiRsuTA. Scop. (Turritis. Linn.) 



Erect, branching; lis. mostly dentate, hirsute, radical ones oblong-ovate, 

 tapering to a petiole, cauline ones oval or lanceolate, sagittate ; 5z7/^i^c5 straight, 

 erect.—® Found in low, rocky grounds, Can. to Va. W. to Oregon. Stems 2 

 or more from the same root, round, hairy at base, near a foot high, dividing 

 into ver>' slender and parallel branches. Leaves scarcely dentate, sessile, Avith 

 heart-shaped or arrow-shaped bases, upper ones acute. Flowers greenish- 

 white. Siliques straight, 1 — 2' long. Jn. 



5. A. HETEROPHYLLA. Nutt. 



Nearly smooth ; radical lis. spatulate, toothed, vppcr ones linear, sessile, 

 entire • siliqve long and spreading ; pet. linear-oblong, exceeding the calyx. — 

 Near Paris. Me., and the White Mts., N. H. Radical leaves somewhat pilose 

 with simple hairs, upper ones linear, about 2' long, and 1—2" wide. Siliques 

 about 3' long. Nnttall. 



