Among all the various plants known to suffer from the attacks of parasites, the vine has been the greatest sufferer. The oïdium, or _Erysiphe Tuckeri_, so called from the name of the discoverer by whom it was first described, has been longest known to the vine grower. This really belongs to the group Ascomycetes, and appears to have been brought from America in 1845, whence it was passed on to France, where it soon threatened to entirely destroy the vineyards. This was followed by another parasite, belonging in this instance to the animal kingdom, _Phylloxera vastatrix_. This oïdium appears on the grape in the form of greyish filaments, terminating in an enlarged head, which contains an agglomeration of spores, not free or in a chaplet, as in Aspergillus (Fig. 273). These spores when ripe burst from the capsule as fine dust, and are diffused by the air in all directions, thus spreading the disease far and away. Another of the parasitic moulds, _Peronospora viticola_, is a kind of mildew, differing from oïdium. The hyphæ penetrate more deeply than that of oïdium. On the upper surface of the leaf brown patches appear; these branch out and ramify as seen in the potato-fungus, _P. infestans_ (Fig. 274). The parasite destroys the tissue of the leaf, and it withers and dies. There are other well-known parasites, the black-rot, _Phomauvicola_, belonging to the Ascomycetes. This appears in early shoots in the form of round black spots, and gradually spreads over leaves and young fruit. This same rot, one year, devastated the American vineyards. [Illustration: Fig. 275.--Fungi, Moulds. _a._ Clustered Spores, _Gonatobotrys simplex_; _b._ Spore of _Puccinia coronata_, the mildew of grapes; _c._ Barley smut; _d._ _Puccinia althæa_; _e._ _Penicillium glaucum_; _m._ _Ixodes farinæ_, found in damaged flour together with smut.]