In lepto and micro forms both aecidiospores and uredospores are absent, the sporidia producing a mycelium which gives rise directly to teleutospores; in the lepto forms the teleutospores can germinate directly, in the micro forms only after a period of rest.
We have thus a series showing a progressive reduction in the complexity of the life-history, the lepto and micro forms having a life-history like that of the Basidiomycetes.
In the hemi, brachy, micro and lepto forms, which possess no aecidium, we find that the association takes place at various points in the ordinary mycelium but always A, Portion of a young aecidium.
Micro and lepto form.
All the forms have the same life-history as the lepto forms of that group, so that there is no longer any trace of sexual organs.
It must be clearly borne in mind that though the Basidiomycetes show no traces of differ entiated sexual organs yet, like the micro and lepto forms of the Uredineae, they still show (in the association of nuclei and later fusion of From Annals of Botany, by permission of the Clarendon Press.