21G MICROSCOPIC FUNGI. 



Peronospora parasitica, Pers. Cabbage Moi-ld; 

 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 diehotomous, 

 rarely trichotomous ; branches always repeatedly trifurcate ; 

 acrospores broadly elliptical, very obtuse at the apex, white. — 

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

 in company with Cystopns ccnulidiis. Summer and autumn. 

 Common. ' (Plate Xlll. fig. 2G2.) 



Peronospora Vicise, Berk. Pea Mould ; fertile threads 

 densely ca^spitose, erect, equal, rarely unequal, 6—7 — 8 times 

 elichotomous ; ultimate ramuli shortly subulate, acute; acrospores 

 ellipsoid, very obtuse at the apex, obtuse or sligiitly acute at the 

 base ; membrane with a violaceous tint. — On Tai'es, Peas, &c. 

 Prequent. (Plate XV. fig..266 ; plate X. fig. 212.) 



Peronospora Arenariae, Berk. Sandwort Mould; 

 fertile threads slender, 6—7 times equally, rarely unequally, 

 diehotomous ; branches spreading ; ultimate ramuli slender, 

 acute, subulate, nearly erect ; acrospores broadly elliptical, 

 oftentimes very obtuse, small ; membrane scarcely violaceous. — 

 On Arenaria serpylli folia and A. trinervis. — June. (Plate VII. 

 fig. 268 ; plate X. fig. 211.) 



Peronospora efTusa, Grev. Spinach Mould ; fertile 

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

 mous above ; acrospores broadly ellipsoid, sometimes verv obtuse ; 

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

 some otlier allied plants. Spring and autumn. Not uncommon. 

 (Plate X. figs. 214, 215.) 



Peronospora Urticse, Casp. Nettle Mould ; fertile 

 threads small, loosely 4— 6 times diehotomous; branches llexuose, 

 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 ^f ould ; fer- 

 tile threads ceespitose, equally or unequally 6—7 times dieho- 

 tomous, rarely trichotomous ; ultimate branches subulate, acute, 

 slightly curved ; acrospores ellipsoid, very obtuse ; membrane 

 with a'slightlv violaceous tint ; oospores large ; epispore brown. — 

 On Lucern \Medicago satira). Highgate and Hampstead, 

 1864. 



