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.
There are, in addition, various other forms (Seroand Exo-sporidia), also primitive in character, but which are as yet too insufficiently known for it to be certain whether they are of distinct ordinal rank, or should be placed with the Haplosporidia.
Forms with septate thallus, and reproduction by chlamydospores which on germination produce sporidia; sexuality doubtful.
D, The sporidia: in B the sporidia have coalesced in pairs at v.
The teleutospore, with the sporidia which arise from it, is always present, and the division into genera is based chiefly on vulgaris, with a, aecidium fruits, p, peridium, and sp, spermogonia.
The teleutospore puts forth on germination a fourcelled structure, the promycelium or basidium, and this bears later four sporidia or basidiospores, one on each cell.
When the sporidia infect a plant the mycelium so produced gives origin to aecidiospores and spermatia; the aecidiospores on infection produce a mycelium which bears uredospores and later teleutospores.
In brachy and hemi the aecidiospores are absent, the mycelium from the sporidia giving origin directly to the uredospores; the former possess spermatia, in the latter they are absent.
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.
In all cases of heteroecism the sporidia infect one host leading to the production of aecidiospores and spermatia (if present), while the aecidiospores are only able to infect another B /., f.
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.
S, Sporidia; st, characterized by having sterigmata; r.