Peronospora parasitica, Pers. Cabbage Mould; threads of the mycelium thickened and much branched; suckers numerous, branched; branches clavate, obtuse; fertile threads thick, soft, flexile, equal or unequal, 5-8 times dichotomous, rarely trichotomous; branches always repeatedly trifurcate; acrospores broadly elliptical, very obtuse at the apex, white.—On Cabbages, Shepherd’s-purse, and other Cruciferæ, sometimes in company with Cystopus candidus. Summer and autumn. Common. ([Plate XIII.] fig. 262.)
Peronospora Viciæ, Berk. Pea Mould; fertile threads densely cæspitose, erect, equal, rarely unequal, 6-7-8 times dichotomous; ultimate ramuli shortly subulate, acute; acrospores ellipsoid, very obtuse at the apex, obtuse or slightly acute at the base; membrane with a violaceous tint.—On Tares, Peas, &c. Frequent. ([Plate XV.] fig. 266; [Plate X.] fig. 212.)
Peronospora Arenariæ, Berk. Sandwort Mould; fertile threads slender, 6-7 times equally, rarely unequally, dichotomous; branches spreading; ultimate ramuli slender, acute, subulate, nearly erect; acrospores broadly elliptical, oftentimes very obtuse, small; membrane scarcely violaceous.—On Arenaria serpyllifolia and A. trinervis.—June. ([Plate XVI.] fig. 268; [Plate X.] fig. 211.)
Peronospora effusa, Grev. Spinach Mould; fertile threads fasciculate, short, thick, 2-6, rarely 7 times dichotomous above; acrospores broadly ellipsoid, sometimes very obtuse; membrane with a violaceous tint. On Spinach, Goosefoot, and some other allied plants. Spring and autumn. Not uncommon. ([Plate X.] figs. 214, 215.)
Peronospora Urticæ, Casp. Nettle Mould; fertile threads small, loosely 4-6 times dichotomous; branches flexuose, ultimate ramuli subulate, arcuate, often deflexed; acrospores large, broadly ovoid or subglobose, distinctly pedicellate; apices very obtuse; membrane violaceous.—On leaves of the common Nettle.
Peronospora trifoliorum, De By. Clover Mould; fertile threads cæspitose, equally or unequally 6-7 times dichotomous, rarely trichotomous; ultimate branches subulate, acute, slightly curved; acrospores ellipsoid, very obtuse; membrane with a slightly violaceous tint; oospores large; epispore brown.—On Lucern (Medicago sativa). Highgate and Hampstead, 1864.
Peronospora grisea, Ung. Veronica Mould; fertile threads erect, fasciculate, grey, 5-7 times regularly dichotomous; branches gradually attenuated; primary oblique erect; others spreading, flexuose; ultimate mostly unequal, slightly arcuate; acrospores ellipsoid or ovoid, obtuse; membrane pale and dirty violet.—On leaves of Veronica beccabunga. May, 1846. ([Plate X.] fig. 213.)
Peronospora arborescens, Berk. Poppy Mould; fertile threads slender, erect, 7-10 times dichotomous above; branches more or less flexuose, squarrose, spreading, gradually attenuated; ultimate ramuli shortly subulate, more or less arcuate; acrospores very small, subglobose; membrane scarcely violaceous.—On the Corn Poppy. June. Common.
Peronospora Schleideniana, De By. (P. Destructor, B.) Onion Mould; fertile threads robust, erect, not septate, branched alternately; ultimate ramuli forked and uncinate or divaricate; acrospores seated on the tips of the ultimate ramuli, obovoid or nearly pear-shaped, attenuated at the base; membrane of a dirty violet-colour.—On the leaves of various species of Allium. Often plentiful. ([Plate XIII.] fig. 263.)
Peronospora violacea, Berk. Scabious Mould; fertile threads branched; acrospores sub-elliptical, violet-coloured. All that is known of this species is contained in the following note from the Rev. M. J. Berkeley:—“It grew on the petals of the common scabious. I have not found it again, and have either lost or mislaid my specimens. You may describe it as læte violacea; floccis ramosis; sporis subellipticis, violaceis. It is probably the Farinaria on Scabious of Sowerby.” (M. J. B.)