APPENDIX. 217 



Peronospora grisea, Vng. Yeronica Mould; fertile 

 threads erect, fasciculate, grey, 5—7 times regularly diclioto- 

 mous; branches gradually attenuated; primary obli(jue erect; 

 others spreading, flexuose ; ultimate mostly unequal, slightly 

 arcuate ; acrospores ellipsoid or ovoid, obtuse ; membrane pale 

 and dirty violet.— On leaves of Veronica heccahunqa. May, 1846. 

 (Plate X. fig. 213.) 



Peronospora arborescens, Berk. Poppy Mould ; fer- 

 tile 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 Bev. 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 Icete violacea ; 

 floccis ramosis ; sporis subellipticis, violaceis. It is probably the 

 Farifiaria on Scabious of Sowerby." (M. J. B.) 



Peronospora sordida, Berk. Eigwort Mould ; forming 

 oad, irregular, dirty, pallid spots on the under surface of the 

 aves ; fertile threads loosely dichotomous above ; tips forked, 



unequal ; acrospores obovate, apiculate. — On leaves of Scrophu- 



laria. Jedburgh. 



Peronospora sparsa, Berk. Bose Mould ; fertile threads 

 scattered, by no means torulose, ultimate branches scarcely unci- 

 nate, dichotomous, pallid grey ; acrospores sub-elliptical. — On the 

 under side of rose-leaves in conservatories. 



Peronospora obliqua, Cooke. Dock Mould ; threads of 

 the mycelium slender ; fertile threads fasciculate, erect, simple, 

 rarely bifurcate, attenuated upwards ; acrospores large, ellipsoid, 

 attached obliquely near the base.— On the under surface of dock 

 leaves. Winter and spring. Probably not uncommon. Brownish 

 circular spots on the leaves indicate the presence of this mould, 

 which is so minute that it might otherwise be overlooked. 

 (Plate XVI. fig. 269.) 



