1. P. Virginiàna, Benth. Stem 1–4° high, terminated by a simple virgate or several panicled spikes; leaves thickish; calyx tubular-campanulate, its teeth half the length of the tube; corolla 1´ long.—Wet grounds, from N. Vt. west and southward. Varies greatly.—Var. denticulàta, Gray. Slender and commonly low, with crenulate-denticulate or obscurely serrate leaves, and slender or loosely-flowered spikes.—Middle Atlantic States.
2. P. intermèdia, Gray. Slender, 1–3° high, remotely leaved; leaves linear-lanceolate, repand-denticulate; spikes filiform, rather remotely flowered; calyx short and broadly campanulate, its teeth about as long as the tube; corolla 5–6´´ long, much dilated upward.—Barrens, W. Ky. and Ark. to La. and Tex.
28. SYNÁNDRA, Nutt.
Calyx bell-shaped, inflated, membranaceous, irregularly veiny, almost equally 4-toothed! Corolla with a long tube, much expanded above and at the throat; the upper lip slightly arched, entire, the lower spreading and 3-cleft, with ovate lobes, the middle one broadest and notched at the end. Stamens 4, ascending; filaments hairy; anthers approximate in pairs under the upper lip; the two upper each with one fertile and one smaller sterile cell, the latter cells cohering together (whence the name; from σύν, together, and ἀνήρ, for anther).
1. S. grandiflòra, Nutt. Hairy biennial, 1° high; lower leaves long-petioled, broadly ovate, heart-shaped, crenate, thin, the floral sessile, gradually reduced to bracts, each with a single sessile flower; corolla 1½´ long, yellowish-white.—Shady banks of streams, S. Ohio to Ill. and Tenn. In spring.
29. MARRÙBIUM, Tourn. Horehound.
Calyx tubular, 5–10-nerved, nearly equally 5–10-toothed, the teeth more or less spiny-pointed and spreading at maturity. Upper lip of the corolla erect, notched, the lower spreading, 3-cleft, its middle lobe broadest. Stamens 4, included in the tube of the corolla.—Whitish-woolly bitter-aromatic perennials, branched at the base, with rugose and crenate or cut leaves, and many-flowered axillary whorls. (A name of Pliny, from the Hebrew marrob, a bitter juice.)
M. vulgàre, L. (Common Horehound.) Stems ascending; leaves round-ovate, petioled, crenate-toothed; whorls capitate; calyx with 10 recurved teeth, the alternate ones shorter; corolla small, white.—Escaped from gardens into waste places. (Nat. from Eu.)
30. BALLÒTA, L. Fetid Horehound.
Calyx nearly funnel-form; the 10-ribbed tube expanded above into a spreading regular border, with 5–10 teeth. Anthers exserted beyond the tube of the corolla, approximate in pairs. Otherwise much as in Marrubium. (The Greek name, of uncertain origin.)