Systematic investigations and phylogenetic analyses have indicated that Astelia, as currently circumscribed, is paraphyletic, with Collospermum nested within it. Further, AsteliasubgenusAstelia is polyphyletic, and Astelia subgenera Asteliopsis and Tricella are paraphyletic, as currently circumscribed. Revision of the subgeneric classification of Astelia is warranted to ensure classification accurately reflects the evolutionary history of these taxa. Collospermum is relegated to synonymy within Astelia. Astelia is dioecious or polygamodioecious, with a superior ovary, anthers dorsi- or basifixed, pistillodes or pistils that have a single short or poorly defined style, a 3 lobed stigma, and fleshy uni- or trilocular fruit with funicular hairs that are poorly to well developed. AsteliasubgenusCollospermum (Skottsb.) Birch is described. A key to Astelia sections is provided. Asteliahastata Colenso, Asteliamontana Seem., and Asteliamicrosperma Colenso pro parte are resurrected and the new combination Asteliasamoense (Skottsb.) Birch, comb. nov. is made.
Keywords: Asparagales; Asteliaceae; Austral; Australia; New Zealand; Pacific; dioecy.