Underground starch storage in Erica species of the Cape Floristic Region -differences between seeders and resprouters

Concentrations of starch in roots of seeder species of Erica from the Cape Floristic Region, South Africa were found to be considerably less than in r esprouters. Shoot starch was highly variable but mean values were similar i n both seeder and resprouter species of Erica. Three distinct patterns of s tarch storage in roots were recognized. All seeder species fell within defi nitions of Categories 1 (narrow major and minor parenchymatous rays, one to two cells wide with no inter-ray storage) or 2 (thick major rays up to sev en cells wide and thin minor rays with small amounts of inter-ray storage) whereas resprouter species were consistently within Categories 2 or 3 (broa d major and minor rays, up to eight cells wide and conspicuous inter-ray st arch storage). Results are discussed in light of similar studies of the rel ated Epacridaceae. 'Mixed' species (i.e. with seeder or resprouter individu als present, often in distinct populations) were always classified as belon ging to Category 2. Studies of populations of three 'mixed' species confirm ed that seeder forms had consistently lower amounts of root starch than res prouters. Rays of xylem parenchyma were the main sites for starch storage i n roots of both seeders and resprouters and greater proportions of cross-se ctional area of roots were consistently devoted to such storage tissues in resprouter forms of the three 'mixed' species. Analyses of a number of seed er and resprouter Erica coccinea populations showed that differences in amo unts of realised and potential root starch storage are best explained by th e effect of regeneration behaviour rather than by among-population variabil ity.