This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Annual or perennial, usually pubescent herbs or shrubs, with opposite, entire or toothed leaves, and small white, pink, or yellowish flowers in axillary clusters which are separated or contiguous. Calyx tubular, 5-10-nerved, slightly 2-lipped, the teeth spine-tipped, the upper middle one broader than the others. Corolla-limb exceeding the calyx, 2-lipped; upper lip entire or lobed; lower lip longer than the upper, with a broad middle lobe. Stamens 4, didynamous, included, the anterior pair the longer; anthers 2-celled, or those of the anterior pair more or less imperfect, the sacs divaricate. Style 2-cleft at the summit, lobes obtuse. Ovary 4-lobed. Nutlets obovoid, smooth. [Greek, iron, referring to its nedicinal use.]
About 45 species, native of the Old World, most numerous in the Orient. Type species: Sideritis hirsiita L.
Sideritis romana L. Sp. Pl. 575. 1753.
Annual, softly pubescent with spreading hairs, the stem erect, 4'-1° tall, usually branched. Leaves obovate to oblong, 1/3'-1 1/4' long, crenate, sessile cr nearly so, ultimately somewhat veiny; clusters few-flowered; flowers white or pinkish; calyx-teeth shorter than the tube, the middle one of the upper lip ovate, all subulate-tipped; corolla slightly exceeding the calyx, the middle lobe of the lower lip reniform.
In fields, southeastern Pennsylvania. Naturalized from the Mediterranean region. Also in Bermuda. June-Aug.