Spatial and Developmental Variation in Seed Dormancy Characteristics in the Fire-responsive Species Anigozanthos manglesii(Haemodoraceae) from Western Australia

Abstract

Anigozanthos manglesii (Haemodoraceae) is a colourful, herbaceous perennial exhibiting intra-and interpopulational variation in germination in response to smoke and heat. This study investigated the extent and nature of this variation in A. manglesii populations collected along a 550 km latitudinal cline from kwongan scrub (308S) to more mesic jarrah forest habitats (348S) in southwestern Australia. Variation in seed germination along a maturing inorescence was also investigated. Germination of this species is known to be prolic following re, and two germination treatments, aerosol smoke and heat, were used as germination cues. There was a trend of increasing responsiveness of A. manglesii to smoke with increasing latitude along a clinal range, but there were no dierences in germination of seeds along the cline in response to control or heat treatments. There was no signicant dierence in intra-population seed germination in response to any treatment. Lastly, a signicant and increasing response to smoke for seeds from the apex to base of the inorescence was detected. This latter trend may be attributed to higher resource allocation and an accelerated after-ripening of basipetal compared to acropetal seeds. Possible reasons for the clinal variation are discussed.