(mycology) A form-genus name applied to a stage of development of a fungus whose aecia have developed but whose species has not been identified.
(botany) The family of diseases marked by this stage of fungus development on a plant.
Origin of aecidium
From New Latin aecidium, the diminutive form of Ancient Greek αἰκία (aikia, “injury”).
New Latin, from Ancient Greek αἰκία (aikia, “injury”) + -idium (“diminutive”)
Aecidium Sentence Examples
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.