CHYTRIDS AND ALGAE: I. HOST–SUBSTRATE RANGE, AND MORPHOLOGICAL VARIATION OF SPECIES OF RHIZOPHYDIUM

Abstract

Studies of pathogenicity and of morphological variation were made with pure cultures of Rhizophydium sphaerocarpum isolated from Spirogyra and of R. karlingii isolated from Ulothrix. R. sphaerocarpum was parasitic, virtually confined to species of Spirogyra amongst which there was a wide range of susceptibility. R. karlingii grew only on non-living algae and on pine pollen. The rhizoidal system of R. sphaerocarpum was quite variable in the extent of its branching. Variations in sporangium size and of the forms of the endobiotic portion of the thallus in R. karlingii grown on different substrates were observed. Such variations have been used in the past as the basis for creation of new taxa. Pathogenicity tests with Paterson's strain of R. sphaerocarpum confirmed that it is saprophytic on many algae and on pine pollen in contrast with the strain isolated from Spirogyra.