Schinzia, which forms galllike swellings on the roots of rushes; Gymnosporangium, causing excrescences on juniper stems; numerous leaf Fungi such as Puccinia, Aecidium, Sep/one, &c., causing yellow, brown or black spots on leaves; or Ustilago in the anthers of certain flowers.
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.
Some very curious details are observable in these cases of malformation, For instance, the Aecidium eta/mum first referred to causes the new shoots to differ in direction, duration and arrangement, and even shape of foliage leaves from the normal; and the shoots of Euphorbia infected with the aecidia of Uromyces Pisi depart so much from the normal in appearance that the attacked plants have been taken for a different species.
Fungus-galls on leaves and stems are exemplified by the pocket-plums caused by the Exoasceae, the black blistering swellings of Ustilago Maydis, the yellow swellings on nettles due to Aecidium, &c.
They are branches in which a perennial Fungus (Aecidium, Exoascus, &c.) has obtained a hold.
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.
In other cases (Diplodia, Aecidium, &c.) conidial or oidial "fructifications" arise by a number of hyphae interweaving themselves into a knot, as if they were forming a sclerotium.
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.
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.
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.
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.
All these forms have of course their aecidium-stage on the barberry.
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.
Vulgaris, with a, aecidium fruits, p, peridium, and sp, spermogonia.