The gelatinous, generally reddish-brown masses of spores - the teleutospores - formed on the juniper in the spring germinate and form minute spores - sporidia - which give rise to the aecidium stage on the pear.
As with other plants, so in fungi the essential process of fertilization consists in the fusion of two nuclei, but owing to the absence of well-marked sexual organs from many fungi, a peculiar interest attaches to certain nuclear fusions in the vegetative cells or in young spores of many forms. Thus in Ustilagineae the chlamydospores, and in Uredineae the teleutospores, each contain two nuclei when young, which fuse as the spores mature.
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.
A, Mass of teleutospores (t) on a leaf of couch-grass.
Host on which the uredospores (if present) and the teleutospores are developed.
Uredospores in the hemi and a, Fertile cells; at a 2 the brachy forms, and before the passage of a nucleus from formation of teleutospores in the adjoining cell is seen.
Mycelium ircdospores otachY' ar Mycelium aecidi'spores teleutospores (young) - mycelium SporoNtyte with conjugate nuclei GametohyEe with single nuclei teleutospores ?(mature) 8a ?; sporida ?m celium erm $ fertile cells Y sp (abortaitviae) (of aecidium) fertilized cells (of aecidium) and bears the basidiospores.
Towards the end of the summer the uredospores are replaced by the winter resting-spores, called teleutospores, which are larger, thicker-walled and darker in colour.
These teleutospores remain inactive on the straw until spring, when they germinate in manure heaps or on moist ground and produce minute sporidia, which are conveyed by air currents to the alternate host, in this case a barberry.
Teleutospores of heteroecious rusts never reinfect the host on which they are produced, so that in many cases the FIG.