the most widespread and common species of sect. Pseudaristea, Aristea spiralis is recognized by the large half to fully nodding flowers, mostly white with light purple markings near the bases of the tepals but in the southern part of its range in the Langeberg and the mountains around Hermanus and Bredasdorp the flowers are an attractive pale blue. It is the only species of Aristea that produces nectar, this secreted from perigonal nectaries at the base of the tepals. The stamens and style extended horizontally and most populations have particularly long filaments, 22–26 mm long, whereas its relatives have filaments 5–6 mm long, or only 3–4 mm in A. pauciflora. The elongate filaments are an adaptation to its unique pollination system. It is the only species of the genus that is pollinated by long-proboscid flies, Philoliche species (Tabanidae). Hovering in a horizontal plane, flies feed on the nectar held in the short perianth tube and while doing so the anthers, held up to 26 mm from the flower, brush pollen against the ventral part of the thorax and abdomen. Stigmas held in the same position as the anthers when receptive and receive pollen from flies that carry pollen of flowers already visited.

Some populations currently included in Aristea spiralis have unusually short filaments but otherwise match the species, having the distinctive strongly compressed, broadly 2-winged flowering stem and tepals with purple markings near the base. Whether flowers of this morph produce nectar or not is unknown. It is noteworthy that plants with both long or short stamens have the same unique pollen grains with rounded, supratectal exine deposits called gemmules.