Barleria mackenii Hook.F.

Subshrub or suffrutex 20-120 cm long, branches erect, straggling or trailing; stems with upper internodes strigulose, lower portion densely (rarely sparsely) and minutely white-velutinous. Leaf buds white-strigulose and often white-velutinous. Leaves ovate to narrowly so or elliptic, 3-12 x 1.2-4.2 cm, base attenuate, apex attenuate or acute, rarely obtuse, apiculate, margin and veins beneath strigulose, upper surface often sparsely strigose, later glabrescent; lateral veins 4-6 pairs; petiole 0-12 mm long. Inflorescence axillary in upper portion of branches, 1-3-flowered; peduncle 1-8 mm long; bracts foliaceous; bracteoles ± ascending, those at distal axils linear to narrowly oblanceolate, 7-20 x 0.5-2.5 mm, those at proximal fertile axils often larger, narrowly elliptic or oblanceolate, 20-37 x 2.5-9.5 mm, margin and midrib strigose; pedicels 1.5-5 mm long. Calyx accrescent; anterior lobe broadly ovate, 13.5-23 x 11-21 mm in flower, 20-32 x 18-25 mm in fruit, base (sub)cordate, apex notched to 4 mm or acute to obtuse, external surface strigose on main veins and margin, internal surface puberulous with mixed eglandular and glandular hairs, venation palmate, prominent; posterior lobe as anterior, 15.5-26 mm long in flower, 23-35 mm long in fruit, apex acute or obtuse, margin often somewhat involute; lateral lobes linear-lanceolate, 7.5-11.5 mm long in flower, 11-14.5 mm in fruit, eglandular-and glandular-pubescent. Corolla 31.5-51.5 mm long, blue, mauve or violet with a darker throat, rarely white throughout, upper tube and limb pubescent externally; tube 14.5-24 mm long, basal 3.5-6 mm cylindrical, 4-6 mm wide, then abruptly funnel-shaped to 8-12.5 mm wide in throat; limb subregular or in weak 4+1 arrangement, all lobes usually strongly imbricate even at anthesis; abaxial lobe 13.5-21 x 12-18 mm, offset by 1.5-4.5 mm; lateral lobes as abaxial but 12.5-21.5 mm wide; adaxial lobes 9-15 mm wide. Stamens attached 4-6 mm from base of corolla; filaments 12.5-22.5 mm long; anthers 3-4.2 mm long; lateral staminodes 0.5-2.2 mm long. Ovary densely eglandular-and glandular-puberulous; style glabrous; stigma 2-3 mm long. Capsule 18.5-21.5 mm long, eglandular-and glandular-puberulous. Seeds 5.5-7.5 x 5-7 mm.