Flora of the Hawaiian Islands
Dicotyledon Literature for Stachytarpheta jamaicensis
Wagner et al., 1990, 1999.
   Verbenaceae -- The Verbena Family Bibliography
      Stachytarpheta jamaicensis

Common name(s): Jamaica vervain, oi, owi
General Information
DistributionNative to tropical and subtropical areas of the New World, now widely naturalized and nearly pantropical.In the Hawaiian Islands, naturalized on Midway, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Low, usually spreading annual or perennial herbs 6-12 dm tall, sometimes somewhat woody toward base, often purplish throughout; stems dichotomously branched, sparsely pubescent or glabrate, nodes usually sparsely pilose.
Leaves often bluish or grayish when fresh, alternate or opposite, somewhat fleshy, oblong to elliptic or ovate, 2-9(-12) cm long, 1.5-4 cm wide, upper surface glabrate, lower surface glabrous to strigose or strigillose on the veins and sometimes margins or sparsely hispidulous, margins serrate, the teeth angled forward, petioles 0.3-3.5 cm long.
Spikes stout and stiff, 15-50 cm long, glabrous, rachis stout and firm, up to 7 mm in diameter, the furrows conspicuously narrower than the rachis, bracts lanceolate or oblong-lanceolate, 5-8 mm long; calyx completely embedded in rachis furrows, somewhat compressed, ca. 5 mm long, 2 of the teeth very reduced; corolla usually pale blue, 8-11 mm long.
2n = 160