Petraea
(Linnaeus dedicated this genus to Robert James, Lord Petre, a famous patron of botany, who died in 1742). ORD. Verbenaceae. A genus comprising about a dozen species of beautiful, twining or arborescent, stove shrubs, natives of tropical America. Flowers violet, purple, or bluish, shortly pedicellate in the axils of the bracts; calyx lobes five, large, prettily coloured at the flowering season; corolla often intensely coloured, with a short tube, and an oblique, five-fid limb; racemes elongated, terminal or in the upper axils. Leaves opposite, coriaceous. The species described below, which are, probably, all in cultivation, should be planted in good, rich mould, and kept in a strong heat. Propagation may be readily effected by cuttings, inserted in light sandy soil, under a glass. P. volubilis is an extremely handsome twiner.
P. arborea (tree-like).* fl. blue, saturated with violet, disposed in copious, axillary or solitary, loose, pendulous racemes, 6in. long. June. l. oblong-lanceolate, obovate-oblong, or elliptic, narrowed at base, 4in. to 7in. long, 1 1/2in. to 2 1/2in. broad, sub-cordate, very shortly petioled, obtuse or retuse, and mucronate at apex, entire. h. 12ft. South America, 1823. Arboreous. (L. B. C. 1606, under name of P. erecta.) P. macrostachya (large-spiked). fl. lilac, disposed in terminal, elongated, pendulous racemes, which are 1 1/2ft. to 2ft. long; pedicels shorter than the calyx tube. June. l. petioled, lanceolate, oblong, or oval-elliptic, 4in. long, 2 1/2in. broad, shortly acuminate at both ends, mucronate, entire, undulated. h. 20ft. South America. Twiner. (P. M. B. iv. 99, under name of P. Stapeliae.) P. rugosa (wrinkled). fl. blue, shortly pedicellate, disposed in axillary or terminal, solitary, erect, loose racemes. July. l. rigid, very shortly petioled, elliptic, sub-cordate at base, and slightly rounded or retuse at apex, mucronate, entire, 2in. to 2 1/2in. long, 1 1/4in. to 1 1/2in. broad, with reflexed margins, reticulately wrinkled above. h. 6ft. to 8ft. Caraccas, 1824. Arboreous.
P. volubilis (twining).* Purple Wreath. fl. purple, on pedicels twice as long as the calyx tube, and disposed in a single, terminal, elongated, nodding raceme, about 6in. long. July. l. 3in. to 4in. long, very shortly petioled, ovate, elliptic, or oblong, rounded or slightly narrowed and loosely cordate at base, acuminate or obtuse, mucronate, entire, undulated. h. 20ft. Panama, &c., to Brazil, 1733. (B. M. 628.)