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72 THE BRITISH SMUT FUNGI<br />

glotose to sub-globose or ovoid, light brown tinged with violet, wall 2 [J, thick.<br />

Epispore hyaline or tinted, reticulate (reticulations l'5-2-0 IJ. diam.), 12-16 ft<br />

diam.<br />

On Knautia arvensis. ' ,<br />

July. England (Yorks.), Scotland (Fife): Uncommon.<br />

Spore germination. Unknown. Some of the records for U: scabiosae may refer to<br />

this species.<br />

Ustilago utriculosa (Nees) Tul.<br />

Caeoma utriculosa Nees, Syst. Pilze, i, p. 14, 1817.<br />

Ustilago utriculosa (Nees) Tulasne, Ann. Sci. nat., Bot., Ser. 3, vii, p. 102, 1847.<br />

Sori in the flowers inflating the ovaries and involving the filaments of the<br />

stamens, about 2-3 mm. long. Spore mass powdery,<br />

brownish violet. Spores globose to sub-globose, violet<br />

when fresh, brownish violet when dry, with prominent<br />

reticulations (2 to 3-4 /Lt wide, 1-5-2 y. deep),<br />

11-14/^ diam. (Fig. 4:b).<br />

On Polygonum lapathifolium and Polygonum sp.<br />

Aug .-Sept. Yorks.<br />

Exsiccati: Vize, Micro. Fungi, 132.<br />

This species is similar to U. anomala (q.v.).with<br />

FIG. 4. o. Ustilago anomala. '^^^^^ i* has been confused. It appears to be of less<br />

Spores from type collection, frequent Occurrence in Great Britain than 17. anomala.<br />

x500. 6. U. utriculosa.<br />

Spores. x500. Spore germination. The four-celled promycehum bears<br />

apical and lateral sporidia which produce secondary<br />

sporidia by budding or germ-tubes. No sporidial or hyphal fusions were observed<br />

by Brefeld (1895) or by Fischer & Hirschhorn (1945 a), but Liro (1924, p. 208)<br />

who germinated spores of this species and of U. anomala records the fusion of<br />

sporidia still attached to the promycelium. Infection of the host occurs at the<br />

seedling stage.<br />

Physiologic races. The net-spored smuts attacking species of Polygonum can be<br />

subdivided into physiologic races some of which diifer slightly in size of spore.<br />

Several races have been given specific rank (Liro, 1924; Ciferri, 1938).<br />

Ustilago anomala Kunze<br />

Ustilago anomala J. Kunze, Fungi select, exsicc, No. 23, 1875.<br />

Similar to U. utriculosa (q.v.) from which it differs in the globose, sub-globose,<br />

or ovoid spores having more delicate reticulations (up to 2 /x wide, about 1 ft<br />

deep) (Fig. 4 a).<br />

On Polygonum convolvulus, P. hydropiper, and P. persicaria.<br />

Aug.-Oct. Widespread. Fairly common.<br />

Spore germination has been described by Schroeter (1877) and Brefeld (1895).<br />

Germination occurs in the spring after overwintering when sporidia are produced<br />

on a four-celled promycelium. The sporidia after fusing in pairs become<br />

detached from the promycehum and then produce germ-tubes or, in nutrient<br />

splution, bud off secondary sporidia to give yeast-like colonies.

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