216 MICEOSCOPIC FUNGI. 



Peronospora parasitica, Pers. Caebage 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 elHptical, very obtuse at the apex, white. — 

 On Cabbages, Shepherd's-purse, and other Cruciferie, sometimes 

 in company with Cystoptis candidus. Summer and autumn. 

 Common. (Plate XIII. fig. 262.) 



Peronospora Vicise, Berk. Pea Mould; fertile threads 

 densely csespitose, 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. 

 Prequent. (Plate XY. fi^, 266 ; plate X. fig. 212.) 



Peronospora Arenariao, Berk. Sandw^ort Mould; 

 fertile threads slender, 6 — 7 times equally, rarely unequallj^, 

 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 YII. 

 •^g. 268 ; plate X. fig. 211.) 



Peronospora efiusa, Grev. Spinach Mould ; fertile 

 threads fasciculate, short, thick, 2—6, rarely 7 times dichoto- 

 mous above ; acrospores broadly ellipsoid, sometimes very obtuse ; 

 membrane with a violaceous tint. On Spinach, Goosefoot, and 

 some other allied plants. Spriug and autumn. Not uncommon. 

 (Plate X. figs. 2M, 215.) 



Peronospora Urticse, 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 trifolioriim, De By. Clovek Mould ; fer- 

 tile threads cgesi)itose, equally or unequally 6—7 times dicho- 

 tomous, rarely trichotomous ; ultimate branches subulate, acute, 

 slightly curved ; acrospores ellipsoid, very obtuse ; membrane 

 with a slightly violaceous tint ; oospores large ; epispore brown. — 

 Ou Lucern {Medicago satica). High gate and Hampstead, 

 lS6i. 



