1. S. cicutæfòlium, Gmelin. Stout, 2–6° high; leaflets 3–8 pairs, linear to lanceolate, sharply serrate and mostly acuminate, 2–5´ long (lower leaves sometimes submersed and finely dissected, as in the next); fruit 1½´´ long, with prominent ribs. (S. lineare, Michx.)—Throughout N. America.
2. S. Carsònii, Durand. Weak, 1–2° high; leaflets 1–3 pairs, linear, sharply serrate, 1–2´ long; when submersed or floating, very thin, ovate to oblong, usually laciniately toothed or dissected, the leaf sometimes reduced to the terminal leaflet; fruit about 1´´ long.—Mass., R. I., Conn., and Penn.
23. BÉRULA, Koch.
Calyx-teeth minute. Fruit nearly round, emarginate at base, glabrous; carpels nearly globose, with very slender inconspicuous ribs and thick corky pericarp; oil-tubes numerous and contiguous about the seed-cavity; seed terete.—Smooth aquatic perennial, with simply pinnate leaves and variously cut leaflets, usually conspicuous involucre and involucels of narrow bracts, and white flowers. (The Latin name of the Water-cress, of Celtic origin.)
1. B. angustifòlia, Koch. Erect, ½–3° high, leaflets 5–9 pairs, linear to oblong or ovate, serrate to cut-toothed, often laciniately lobed, sometimes crenate (½–3´ long); fruit scarcely 1´´ long. (Sium angustifolium, L.)—Throughout the U. S. July, Aug.
24. ZÍZIA, Koch.
Calyx-teeth prominent. Fruit ovate to oblong, glabrous, with filiform ribs; oil-tubes large and solitary in the broad intervals, and a small one in each rib; stylopodium wanting; seed terete.—Smooth perennials (1–3° high), with mostly Thaspium-like leaves, no involucre, involucels of small bractlets, yellow flowers, and the central fruit of each umbellet sessile. Flowering in early spring in open prairies and upland meadows. (Named for I. B. Ziz, a Rhenish botanist.)
1. Z. aùrea, Koch. Leaves (except the uppermost) 2–3-ternate the radical very long-petioled; leaflets ovate to lanceolate, sharply serrate; rays 15–25, stout (1–2´ long); fruit oblong, about 2´´ long. (Thaspium aureum, var. apterum, Gray, Manual.)—Atlantic States, west to Minn. and Tex.
Var. Bébbii, Coult. & Rose. A more slender mountain form, with leaflets more coarsely serrate, the radical leaves smaller and more simple; rays 2–8, slender (2–3´ long); fruit oval, 1–1½´´ long.—W. Va. and Va. to Ga.
2. Z. cordàta, DC. Radical leaves mostly long-petioled, cordate or even rounder, crenately toothed, very rarely lobed or divided; stem-leaves simply ternate or quinate, with the ovate or lanceolate leaflets serrate, incised, or sometimes parted; fruit ovate, 1½´´ long. (Thaspium trifoliatum, var. apterum, Gray, Manual.)—Same range as the preceding, but extending farther westward.