1G8 XIII. CRUCIFER^. Sisymbrium. 



valves, opening elastieally ; placentae not winged ; seeds in a single 

 row, ovate, not bordered ; funiculus slender, 0=. — Rhizoma %. Lvs. 

 divided, often but 2 or 3. Fls. white or purplish. 



1. D. DiPHYLLA. Pepper Root. 



St. 2-leaved ; Ifts. ternate, subovate, unequally and incisely dentate ; 

 rhiz. dentate. — In woods and wet meadows, Can. to Car. and to the Miss. Stem 

 about If high, round, smooth, with 2, nearly opposite, ternate leaves above the 

 middle. Leaflets on very short stalks, the lateral ones oblique, all with rounded, 

 mucronate, unequal teeth. Flowers racemed, large, white ; the petals much 

 larger than the calyx. The rootstock is long and large in proportion to the 

 plant, beset with teeth, with a pungent, aromatic taste. May. 



2. D. LACiNiATA. Muhl. (D. concatenata. Michx.) 



Rhiz. moniliform ; cavline lvs. 3, 3-parted, the divisions lanceolate or 

 linear-oblong, incisely toothed or pinnatifid, lateral ones lobed. — In woods. Can. 

 and U. S. The rootstock consists of several tubers of a pungent taste. Stem 

 If high, smooth, simple. Leaves usually in a whorl about half-way up, the 

 segments with very irregular, mucronate teeth, rarely subentire, lateral ones 

 cut nearly to the base, rendering the leaf almost quinate. Root-leaves some- 

 times 0. Flowers racemed, purplish. Apr. May. 



3. D. MAXIMA. Nutt. 



St. tall ; lvs. alternate, 5 — 7, remote, the margin a little roughened ; Ifts. 

 somewhat oval, incisely and acutely dentate, lateral ones lobed. — Western 

 N. Y. and Penn. Tubers of the rhizoma concatenate. Stem often nearly 2f 

 high. Flowers pale purple. 



4. D. HETEROPHYLLA. Nutt. 



Rhiz. moniliform, with oblong tubers ; radical lvs. on long petioles, 

 deeply and obtusely lobed, lobes crenate-dentate with abruptly mucronate teeth, 

 caiiline lvs. 2, rarely 3, alternate, petiolate, ternately divided, segments linear- 

 lanceolate, entire or rarely toothed, rough-edged. — Woods, Penn. to Ky. Stem 

 8—12' high. Cauline leaflets 1—2' long, 2—3" wide. Corymb with about 9 

 pale purple flowers. Jn. 



18. HESPfiRIS. 



Gr. tanepis, evening; when the flower is most fragrant. 



Calyx closed, furrowed at base, shorter than the claws of the petals ; 

 petals bent obliquely, linear or obovate ; silique 4-sided, 2-edged or 

 subterete ) seeds not margined ; stigmas forked, with the apices con- 

 verging. 



1. H. MATRONALis. RocJcet. 



St. simple, erect ; lvs. lanceolate, ovate, denticulate ; pet. emarginate, 

 mucronate ; pedicels as long as the calyx. — A fine garden perennial, said to be 

 found native about Lake Huron. Stem 3 — it' high. Flowers purple, often 

 double, and white in /?. hortensis. f 



2. H. APRiCA. Siberian Rocket. — St. erect, simple, pubescent; lvs. oblong, 

 obtuse, entire, ciliate-hispid; pedicels as long as the calyx. — % From Siberia. 

 Stem a foot high. Flowers purple. May. Jn. f 



19. SISYMBRIUM. Allioni. 

 Calyx mostly spreading, equal at base ; petals unguicuiate, entire ; 

 silique subterete ; valves concave ; style very short ; seeds in a sin- 

 gle series, ovoid; cotyledons OJI, sometimes oblique. 



1. S. OFFICINALE. Scop. (Erysimum. Linn.) Hedge Mustard. 



Lvs. runcinate ; rac. slender, virgate ; siliqucs subulate, erect, closely ap- 

 pressed to the rachis. — A common and troublesome weed, in fields, road- 

 sides, rubbish, &c.. Can. and U. S. Stem 1 — 3f high, round, more or less hairy, 

 with .spreading branches. Lower leaves 3 — 8' by 1 — 3', the lower segments 

 placed at right angles to the midvein, or pointing backwards, the terminal seg- 



