Reproductive Strategies Matter for Rare Plant Conservation: Pollination, Phenology, and Mating in an Endemic Plant of the Sky Islands of Arizona,Erigeron lemmoniiA. Gray (Lemmon's Fleabane) (Asteraceae)

Abstract

Abstract. Erigeron lemmonii A. Gray is extremely rare, but not endangered. There are fewer than 1000 individuals, but they compose an apparently stable, heterozygotic, diploid (2n = 18) population. The plants are perennial and endemic to one small location (about 0.5 km2) in Scheelite Canyon, Huachuca Mountains (Cochise County), Fort Huachuca Army Base, part of the Sky Island region, Arizona. Erigeron lemmonii grows from crevices in cliffs, ledges, and rock faces where it can form mats by spreading vegetatively from the roots as they proliferate, especially in microsites where soil accumulates. Our goals were to (1) investigate floral anatomy for reproductive structures (inflorescences, florets, and pollen), (2) record flowering phenology, and (3) determine the species' breeding and mating system. Inflorescence anatomy and development are typical for Erigeron with ray (pistillate) and disc (bisexual) florets. Stigmas of the disc florets do not fully exsert and reflex, though they do present and expose the...