PATTERNS OF ROOT COLONIZATION IN EPACRIDACEOUS PLANTS COLLECTED FROM DIFFERENT SITES

Root colonization was studied in ten species of the Epacridaceae at th ree sites in Victoria by morphological and cross-inoculation experimen ts. The sites and genera chosen were Cranbourne [Epacris impressa Labi ll. and Leucopogon ericoides (Smith) R. Pr.] and Rye [L. parviflorus ( Andrews) Lindley] on the Mornington Peninsula, and the Grampians [Astr oloma conostephioides (Send.) Benth., A. humifusum (Cav.) R. Br., A pi nifolium (R. Br.) Benth, Brachyloma daphnoides (Smith) Benth., E. impr essa, E. impressa var. grandiflora Benth. and Styphelia adscendens R. Br.] in western Victoria. For morphological studies, samples of roots from each species al each site were cleared and stained and examined m icroscopically. For cross-inoculation studies, cuttings from each site were struck in potting medium inoculated with soil from the same and other sites. The ericoid mycorrhizae in the roots of plants found al o r grown in Cranbourne and Rye soils were similar. Both were significan tly different from the internal hyphae found in the roots of plants fo und at or grown in Grampians soils: which were three times larger in d iameter and formed dense coils which filled the host cell and invaded adjacent epidermal cells. This suggests that more than one fungus is i nvolved in the relationships, that the Mornington Peninsula sites had a different fungus from the Grampians site and that host specificity i s low. Vesicular structures were also found commonly on plants at the Grampians site, in contrast with other sites. (C) 1996 Annals of Botan y Company