Pycnostachys
(from pyknos, dense, and stachys, a spike; referring to the dense flower-spikes). SYN. Echinostachys. ORD. Labiatae. A small genus (six species) of erect-growing, stove, annual or perennial herbs, natives of tropical or sub-tropical Africa and Madagascar. Flowers in whorls, which are disposed in dense, terminal spikes; corolla blue, with an exserted, defracted tube, two-lipped, the upper lip four-toothed, the lower entire and concave; calyx ovoid-campanulate, equal, with five subulate-spinose teeth. Nutlets almost round, smooth. Leaves stalked, linear-lanceolate to broadly ovate, coarsely toothed. Only two species have been introduced to our gardens. For culture, see Ocimum.
P. caerulea (blue). fl., corolla blue; calyx sessile; spike from 1in. to 2in. long. August. l. sessile, oblong or linear-lanceolate, 2in. to 3in. long, acute, slender, deeply serrated, entire, and narrowed at base, glandulose beneath. Stem over 1ft. high, tetragonal. Madagascar, 1825. Annual. (H. E. F. 202.) P. urticifolia (Nettle-leaved). fl. blue; upper lip of corolla erect, with four incurved lobes; lower one concave; spike terminal, ovate, acuminate, large, thyrse-like. August. l. ovate, acuminate, truncate or very obtuse at base, sub-cuneate, long-stalked, deeply serrated, pubescent beneath. h. 3ft. Africa, 1862. Perennial. (B. M. 5365.)