MUCEDINES. 593 



1774. Pexonospora iufestans. Mont. " Potato Peronospora." 



Threads of mycelium slender, always destitute of suckers ; 

 fertile threads thin, gradually attenuated upwards, with one to 

 five branches, one or more inflated vesicles near the apices of 

 the branches ; branches either simple or with short branchlets ; 

 acrospores ellipsoid or ovoid, apex furnished with a prominent 

 papilla. — Cooke Micro. Fungi^ 1. 14,/. 264. Fop. Sc. Rev. iii. t. 8, 

 /. 3. Botrytis infestans. B. ^' Br. Ann. N.H. no. 521. Journ. 

 Hort. Soc.i. t. 4:. De Bary Ann. Sc. JSfat. (1863). xx. t. 5, 6. 

 Desm. exs. no. 1492. Rabh. exs. no. 1879. Fckl. exs. no. 37. Cooke 

 exs. no. 192. Berk. exs. no. ^4^0. 



On potato stems, leaves, and tubers, &c. Common. 



Producing the well-known potato disease. 



1775. Peronospora nivea. Ung. *' Parsnip Peronospora." 



Threads of mycelium stout, often torulose ; suckers nume- 

 rous, vesicular, obovate ; fertile threads fasciculate, dwarfish, 

 tapering or subulate, or once or twice shortly bifurcate, rarely 

 trifurcate, with one to four horizontal branches near the summit, 

 once, twice, or three times bifurcate ; acrospores subglobose or 

 ovoid, with an obtuse papilla at the apex, — Cooke Micr. F. p. 

 Botrytis macrospora. Ung. exs. t. 2, /. 14. B. Sf Br. Ann. N.H. 

 no. 627. Rabh. exs. no. 1172, F.E. no. 376. Fckl. exs. no. 27. 

 Cookeexs.no. Idl. Botrytis cnistosa Fr. Berk. exs. no. 332. Eng. 

 Fl.Y.p.343. 



On various Umbellifers. 



The roots of the plants which are infested with this mould are generally 

 diseased, like the tubers of potatoes attacked by P. infestans. 



1776. Peronospora pygmaea. Ung. " Anemone Perono- 



spora." 



Threads of mycelium thickened, often constricted and vari- 

 cose ; suckers minute, obovate, or pear-shaped ; fertile threads 

 fasciculate (2-5 or more), simple above, or divided at the apex 

 into 2-4 short simple branches, or shortly twice dichotomous, or 

 all simple, obtuse, surmounted by 2-4 short spicules ; acrospores 

 ovoid or elhpsoid, variable in size ; apices broadly and obtusely 

 papillate.— Coo/je Micr. Fung. 1. 15. /. 267. Uny. Bot. Zeit. 1847, 

 t. Q,f.8. Botrytis curta. Berk. Ann. N.H. no. 128, t. S, f. 13. 

 Berk. exs. no. 20d. Corda.\.f.21. Rabh. exs. no. 37 3,37 4. Fckl. 

 exs. no. 2. 



2c 



