1. Ruellia blechum Linnaeus, Syst. Nat., ed. 10. 2: 1120. 1759.
赛山蓝 sai shan lan
Barleria pyramidata Lamarck; Blechum brownei Jussieu; B. pyramidatum (Lamarck) Urban.
Herbs to 50 cm tall. Roots lacking tuberlike swellings. Stems slightly 4-angled, often prostrate and rooting at nodes, sparsely pubescent to subglabrous. Petiole 0.5-2.5 cm, strigose; leaf blade ovate, 3-6 × 2-4 cm, abaxially paler and subglabrous, adaxially green, sparsely strigose and densely pilose along veins, secondary veins 5-8 on each side of midvein, base obtuse to rounded and slightly decurrent onto petiole, margin entire, apex acute. Inflorescences terminal, dense spikes, 2-6 cm, subsessile to shortly pedunculate; rachis strigose; bracts subleaflike, ovate, ca. 1.5 × 1.3 cm, abaxially slightly pubescent, margin ciliate; bracteoles 2, lanceolate-ovate, 5-9 × 1.5-3 mm, margin ciliate. Calyx lobes linear to subulate, outside pilose. Corolla white to pale blue, ca. 1.5 cm (cleistogamous flowers sometimes present, these much smaller and budlike), outside puberulent on lobes; lobes ovate, ca. 3 × 2 mm. Stamens with longer pair ca. 4 mm and shorter pair ca. 3 mm; filaments glabrous; anther thecae ca. 1 mm. Ovary comose; style 6-10 mm, slightly hirsute; stigma usually with only 1 lobe evident. Capsule substipitate, ovoid to ellipsoid, ca. 6 mm, puberulent, 8-12-seeded; septa with attached retinacula separating from inner wall of mature capsule. Seeds ca. 1.5 mm in diam., margin with a conspicuous band of appressed hygroscopic trichomes. Fl. Nov, fr. Nov. 2n = 34.
Disturbed sites, drainage ditches; sea level to below 100 m. Naturalized in Taiwan [native to tropical America].
Ruellia blechum is widely naturalized in tropical and subtropical areas.