Erect, much-branched shrub, 0.2-0.8 m tall, branchlets often spiny. Leaves clustered, narrowly linear, 4-13 mm long, spine-tipped, straight or rarely ± reflexed, minutely ciliolate near base, secondary ones smaller. Flowers sessile, axillary, white, with dark purple keel. Capsule with prominent leaf-like horns.
Intricately branched shrublet, mostly to 40 cm, branchlets often spiny. Leaves fascicled, sessile, linear, channelled, spine-tipped. Flowers sessile, axillary, white with purple keel. Capsules prominently horned.