A Remnant Greensword Population from Pu'u 'Alaea, Maui, with Characteristics of Argyroxiphium virescens (Asteraceae)

Abstract

Two unusual greenswords occurring on Pu'u 'Alaea in 1989 reportedly possessed vegetative features characteristic of the presumed extirpated species Argyroxiphium virescens Hillebr. One of these Pu'u 'Alaea plants flowered in August 1989, allowing detailed comparisons with preserved specimens of A. virescens as well as other species and hybrids of Argyroxiphium native to East Maui. These comparisons suggest that the unusual Pu'u 'Alaea greenswords represent remnants of hybridization between the now presumably extinct A. virescens and the more common Haleaka silversword, A. sandwicense subsp. macrocephalum (A. Gray) Meyrat, that still occurs at and adjacent to this site. The estimated pollen fertility of 62% in the Pu'u 'Alaea plant is consistent with this interpretation. Recovery of a few embryos from fruits of the plant that flowered in 1989 and the possibility of tissue culture of the remaining living plant at Pu'u 'Alaea apparently represent the last opportunities to conserve any vestige of A. virescens.