Pignut

Mesosphaerum suaveolens is an erect, strongly aromatic annual or short-lived perennial herb of the Lamiaceae family growing 0.5-2 m tall with a stout woody base when older. Stems are square in cross-section, branched, ribbed and densely clothed with soft white hairs together with sessile yellow glandular dots that release a pungent, somewhat mint-like fragrance when crushed. Leaves are opposite, ovate to broadly ovate, 3-10 cm long, with serrate-crenate margins, an acute apex, a truncate to subcordate base and a softly pubescent texture on both surfaces. The inflorescence consists of small, dense, axillary cymes of 2-10 flowers borne on slender peduncles in the upper leaf axils, the whole forming an elongate leafy raceme. Flowers are about 5-8 mm long with a tubular ten-ribbed calyx that enlarges and becomes spiny-toothed in fruit, and a bilabiate bluish to violet corolla with a hooded upper lip and three-lobed lower lip. The four small nutlets are flattened, dark brown and become mucilaginous when wet. Native to tropical America and now pantropical, common on disturbed ground, roadsides and abandoned fields.