CONIDIOPHORES WITH CONIDIA in dense conglomerations, on the whole under leaf surface.
CONIDIOPHORES (cp) 150-400 x 7-10 µm, not thickened or slightly thickened, up to 12 µm at the base, branched 5-7 times.
Branches curved, with final beaklike or forked branches, slanted at a right angle, up to 15 µm long, 1.5-2.5 µm thick at the base.
CONIDIA (c) widely ellipsoidal, or almost globose, rounded at both tips, rarely slightly sharpened at the base, yellowish, 22-30 x 20-26 µm.
OOGONIA 35-47 µm, with a yellowish, up to 2 µm thick wall.
OOSPORES 25-32 µm diam, with a thick, slightly plicate episporium.
PLANT HOST AND DISTRIBUTION. Peronospora ranunculi affects different plant species of the genus Ranunculus.
The fungus has a worldwide distribution (Kochman and Majewski 1970).
NOTES. Peronospora ranunculi routinely causes systemic infection of its plant hosts. Infected plants are yellow-discoloured, do not bloom at all or bloom poorly, and later their leaves are smaller and earlier die.
Kochman J., Majewski T. 1970. Grzyby (Mycota) IV. Glonowce (Phycomycetes), Wroslikowce (Peronosporales). Warszawa, 308 pp.