Double-Spike Bluethread is an erect herb up to
about 70 cm tall with 1-3 unbranched leafy peduncles, hairless. Leaves
are spreading in a basal rosette, smaller and more erect on the stem,
linear to lanceshaped or elliptic, 1-13 cm long, 2-10 mm wide, tip
pointed to long-pointed and sometimes with glandular hairs. Blade is
stalkless and stem-clasping
with a sheathing base. Flowers are usually borne in a pair of up to
15-flowered spike-like branches, 0.6-7 cm long. Peduncle is 2-13 cm
long, flowers stalkless, bracts 3-11 mm long. Flowers are 0.8-3 cm
long, blue with yellow bands, tube 8-30 mm long, 3-8 mm in diameter,
3-winged, lobes 0.5-3 mm long. Capsule is ellipsoid to ovoid, 3-ridged
6-20 mm long. Double-Spike Bluethread is China, Nepal, India, SE Asia
and Australia, at altitudes of 400-3000 m.