DIDYNAMIA, GYMNOSPERMIA. 
to think it indigenous, having found it abundant along the 
banks of the Ohio and Potomac, remote from settlements. In 
wastes and hedges, common. Perennial. May to August. 
272, MARRUBIUM. Gen. pi. 976, {Labiatce,) 
Calix salvevform, rigid, 10-striate. Upper 
lip of the corolla bifid, linear, straight. — 
JYuU. 
1. M. leaves subrotund, ovate, dentate, rugose- 
veined j calix teeth setaceous, hooked. — Willd. 
Icon. FI. Dan. 1036. Engl. Bot. 410. 
Horehound. 
Also plentifully naturalized in wastes. Whole plant of a 
grey aspect. Flowers white. Much used as a domestic medi- 
cine. Perennial, July. 
273. PYCNANTHEMUM. Mich. fl. am. 2.p.7. {Labiata.) 
Capitulum surrounded by an involucrum of 
many bractes. — Calix tubular, striate, 5- 
toothed. Upper lip of the corolla nearly 
entire; lower trifid. Middle segment 
longer. Stamina distant ; cells of the an- 
thers parallel.’’ K. Brown. — J\Tutt. 
1. P. leaves oblong-ovate, acute, subserrate, cano- 
tomentose ; capituli compound, tlie lateral ones 
pedunculated ; bractes setaceous. — Mich, and 
Pursh, 
Clinopodium incanum, L. 
Origanum incanum, Walt. 
Icon. Pluk. mant. t. 344. f. 7. (Pursh.) 
Hoary Basil. 
About three feet high. Whole plant grey or hoary. Flow- 
ers white and pale-red. It possesses the fine odour of Origanum 
