Root hairs and phycomycetous mycorrhizas in phosphorus-deficient soil

Summary Coprosma robusta formed phycomycetous mycorrhizas in unsteamed forest soil and grew equally well with or without added phosphate. In steamed soil it did not grow unless phosphate was added. Of the other species tested (Leptospermum scoparium, Solanum nigrum, Lolium perenne, Hakea enkiantha, Histiopteris incisa, Marchantia berteroana) most formed mycorrhizas in unsteamed soil, but all grew better in steamed soil. The dry matter of the mycorrhizal Coprosma seedlings contained the highest concentration of phosphorus, but the relatively large plants that the other species produced in steamed soil contained a greater total quantity. It is suggested that this entered mainly through their extensive root hairs (or rhizoids), and that lack of root hairs in Coprosma and other woody species explains their need for added phosphate when mycorrhizas are not formed.