The extraordinary malformations known as Witches Brooms, caused by the repeated branching and tufting of twigs in which the mycelium of Exoascus (on birch) or Aecidium (on silver fir) are living, may be borne in considerable ntimbers for years without any very extensive apparent injury to the tree.
We find a 3 thus that in the eu and opsis forms the association of nuclei takes place at the base of the aecidium which produces the aecidiospores.
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 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.
Vulgaris, with a, aecidium fruits, p, peridium, and sp, spermogonia.
In due time the fungus, known as Aecidium Berberidis, appears on the barberry leaves in the form of small cluster-cups on aecidia, each of which is filled with chains of orange-coloured aecidiospores.