166 XIII. CRUCIFE-R^E. ARABIB 



1. T. GLABHA. Smooth Tower Mustard. 



St. erect; radical Ivs. petiolate, dentate, with ramose hairs, cauline u-mx 

 broad-lanceolate, sagittate, half-clasping, glaucous, smooth; siliques erect. 

 Shores of Lake Superior, W. to the Rocky Mts. Naturalized about New 

 Haven. Eaton. Stem round, simple, IJf high. Leaves 1 2' long. Siliques 

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



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

 repand-denticulate, cauline entire. Watertown, N. Y., on rocks. Torrey <$ Gray. 



2. T. BRACHYCARPA. Torr. & Gray. 



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

 lanceolate, sagittate and subamplexicaul ; siliques short, linear-oblong ; pedicels 

 pendulous in ilower, spreading in fruit. (g) Lake shores, Mich. Stem 1 2f 

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

 Siliques 1' long, spreading. 



15. ARAB1S. 



Said to derive its name from Arabia, its 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. Michx.} Sickle Pod. 



Cauline Ivs. sessile, oblong-lanceolate, narrow at base, pubescent ; pedi- 

 cels pubescent, reflexed in the fruit; silique subfalcate, veined, pendulous; sds. 

 winged. QJ. On rocky hills, Can. to Ga. W. to Ark. A plant remarkable for 

 its long, drooping pods, which resemble a sickle blade, or rather a curved 

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

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

 with narrow bases, remotely denticulate. Flowers small, white. Pods slen- 

 der, flattened, nearly 3' long. Jn. 



2. A. LYRATA. (Sisymbrium arabidoides. Darl.} 



St. and upper Ivs. smooth and glaucous ; radical Ivs. lyrately pinnatifid, 

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

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

 leaves numerous, rosulate, 1 3' long, \ as wide, petiolate, lower stem-leaves 

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

 middle size. Siliques when mature 1| 2' long, less than 1" wide. Apr. May. 



3. A. LJEVIQATA. DC. (Turritis laevigata. Muhl.} 



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

 tiole, dentate, stem Ivs. linear-lanceolate, amplexicaul, obtuse, upper ones entire; 

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

 spreading and pendulous ; sds. winged. QJ. In rocky woods and low grounds* 

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

 Root-leaves often purplish, f !' long, | as wide, with acute teeth. Stem- 

 leaves 2 5' long, | as wide, upper ones entire. Flowers in long racemes. 

 Siliques 2 3' long, scarcely \" wide. May. 



4. A. HIRSUTA. Scop. (Turritis. Linn.") 



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

 tapering to a petiole, cauline ones oval or lanceolate, sagittate ; siliques 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 very slender and parallel branches. Leaves scarcely dentate, sessile, with 

 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 Ivs. spatulate, toojthed, upper ones linear, sessile, 

 entire ; silique long and spreading ; pet. linear-oblong, exceeding the calyx. 

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

 v?ith simple hairs, upper ones linear, about 2' long, and 1 2" wide. Siliquea 

 about 3' long. NuttaU. 



