Spatial and developmental variation in seed dormancy characteristics in the fire-responsive species Anigozanthos manglesii (Haemodoraceae) from western Australia

Anigozanthos manglesii (Haemodoraceae) is a colourful. herbaceous perennial exhibiting intra- and interpopulational variation in germination in respon se to smoke and heat. This study investigated the extent and nature of this variation in A. manglesii populations collected along a 550 km latitudinal dine from kwongan scrub (30 degreesS) to more mesic jarrah forest habitats (34 degreesS) in southwestern Australia. Variation in seed germination alo ng a maturing inflorescence was also investigated. Germination of this spec ies is known to he prolific following fire, and two germination treatments, aerosol smoke and heat, were used as germination cues. There was a trend o f increasing responsiveness of A. mangiesii to smoke with increasing latitu de along a clinal range, but there were no differences in germination of se eds along the cline in response to control or hear treatments. There was no significant difference in intra-population seed germination in response to any treatment. Lastly, a significant and increasing response to smoke for seeds from the apex to base of the inflorescence was detected. This latter trend may be attributed to higher resource allocation and an accelerated af ter-ripening of basipetal compared to acropetal seeds. Possible reasons for the clinal variation are discussed. (C) 2001 Annals of Botany Company.