This species is characterized by small triangular stipules; medium-sized leaves; terminal and/or axillary, rather lax cymose inflorescences; small calyx lobes; rather small corollas with slender cylindrical tubes; and small fruits. Puff & Buchner (1994) considered this to be the species most closely related to the single African species of the genus, Danais xanthorrhoea. Danais rhamnifolia is widely distributed in Madagascar and appears to be at least sometimes locally frequent, or frequently collected.

Danais rhamnifolia is quite similar to several other frequently encountered species, Danais ligustifolia, Danais breviflora, and Danais microcarpa. Puff & Buchner separated these others by their corollas with a funnelform tube, shorter inflorescences, and leaves generally smaller or at least proportionately narrower.