13. HÉSPERIS, Tourn. ROCKET. Pod linear, nearly cylindrical; stigma lobed, erect. Seeds in 1 row in each cell, oblong, marginless. Cotyledons incumbent.--Biennial or perennial, with serrate sessile or petiolate leaves, and large purple flowers. (Name from ἑσπέρα, evening, from the evening fragrance of the flowers.) H. MATRONÀLIS, L. (DAME'S VIOLET.) Tall; leaves lanceolate, acuminate, mostly petiolate; pods 2--4´ long, spreading.--Sparingly naturalized. (Nat. from Eu.) 14. ERÝSIMUM, Tourn. TREACLE MUSTARD. Pod linear, 4-sided, the valves keeled with a strong midrib; stigma broadly lobed. Seeds in 1 row in each cell, oblong, marginless. Cotyledons (often obliquely) incumbent.--Chiefly biennials, with yellow flowers; the leaves not clasping. Pubescence of appressed 2--3-parted hairs. (Name from ἐρύω, _to draw blisters_.) 1. E. ásperum, DC. (WESTERN WALL-FLOWER.) Minutely roughish-hoary; stem simple, leaves lanceolate to linear, entire or somewhat toothed; _pods nearly erect_ or widely spreading _on short pedicels, elongated_ (3--4´ long), exactly 4-sided; stigma 2-lobed.--Ohio (on limestone cliffs) to Ill., Ark., Dak., and common westward. June, July.--Plant stout, 1--2° high; the crowded bright orange-yellow flowers as large as those of the Wall-flower. Petals orbicular, on very slender claws. 2. E. cheiranthoìdes, L. (WORM-SEED MUSTARD.) Minutely roughish, branching, slender; leaves lanceolate, scarcely toothed; flowers small; _pods small and short_ (7--12´´ long), very obtusely angled, ascending on slender _divergent pedicels_.--Banks of streams, Mass. to Penn., Minn., and northward. July. (Eu.) 3. E. parviflòrum, Nutt. Stem erect, often simple; leaves linear-oblanceolate, entire or the lowest coarsely toothed; flowers small (3´´ long); pods narrow, 1--2½´ long, ascending on short pedicels.--Minn. to Kan. and westward. 15. SISÝMBRIUM, Tourn. HEDGE MUSTARD. Pod terete, flattish or 4--6-sided, the valves 1--3-nerved; stigma small, entire. Seeds oblong, marginless, in 1 or 2 rows in each cell. Cotyledons incumbent. Calyx open.--Flowers small, white or yellow. Pubescence spreading. (An ancient Greek name for some plant of this family.) Ours are mostly annuals or biennials. 1. S. hùmile, Meyer. Perennial, branching from the base, sparingly pubescent, 6´ high or less; leaves narrowly oblanceolate, mostly coarsely and sharply toothed; flowers white or rose-color; pods very narrow, subterete, 4--9´´ long, ascending on short pedicels, beaked with a short style, seeds 1-ranked. (Arabis petræa, _Man._, not _Lam._)--Willoughby Mountain, Vt.; Canada and westward. (N. Asia.) 2. S. canéscens, Nutt. (TANSY MUSTARD.) _Leaves 2-pinnatifid_, often hoary or downy, the divisions small and toothed; flowers yellowish, very small; pods in long racemes, oblong-club-shaped or oblong-linear, shorter than their mostly horizontal pedicels; _seeds 2-ranked_ in each cell.--Penn. and N. Y. to Lake Superior, thence southward and westward. June--Aug.