I
I.
The Parasitic Slime-Moulds.
The following species of the genus are recognized:
S. Veronica Schrör.
35
Schröter, J. Cohn's Kryptogamenflora von Schlesien, Vol. 3. Pp. 1-
500. 1886-1897.
Spore-balls nearly spherical, 18-28μ in diameter. Spores ovoid, 8p 9p long x 4μ-5μ wide. Spore coat thin and smooth. On germina- tion swarm spores fuse, and form plasmodia. When mature, plasmodia become converted into single spore-balls. The fungus attacks the cortical region of the stem and petiole, causing hypertrophy. Tumours being up 10 5mm. in diameter. It has been recorded in Veronica hederifolia and in V. triphyllae in Germany; V. hederifolia in Denmark; in V. arvensis and V. Chamaedrys in France and in V. Chamaedrys in Southern England.
The detailed accounts of this species given by Blomfield and Schwartz (2) in England, and Maire and Tison (3) in France.
2.
S. radicale Cook & Schwartz. (Pl. 14, fig. 2).
Cook, W. R. Ivimey and Schwartz, E. J. Ann. Botany. Vol. 43.
Pp. 81-88. 1929.
Spore-balls ellipsoidal or oval, with large central hollow, 20μ—57) long by 16-20 in diameter. Spore-ball enveloped in a common mem- brane. Individual spores oval 4μ x 3p in diameter. On germination they give rise to pyriform swarm spores. Plasmodia small, at maturity each plasmo dium forming a single spore-ball. The organism only attacks root-hairs which as a result are enlarged and swollen at the point where the plasmodium lies. The organism has never been found in the piliferous layer or the cortex. It has been found attacking various species of grasses which were growing around the margin of large stretches of water in two localities in South-east England, at Dunton Green, Kent, and Crawley, Sussex.
The spores are smaller than those of S. Veronica and are more com- parable with those found in other genera, The hypertrophy is restricted to the root-hairs and therefore infected plants cannot be easily recognized, though the slight reddening of the leaves of the host is a helpful sign of the presence of the fungus. In the appearance of the spore-ball this species is more typical of the genus Sorosphæra than is S. Verónica. Genus 3. Sorodiscus Lagerheim & Winge.
Winge, O. Archiv. f. Bot. Vol. 12. Pp. 139. 1912.
Spores aggregated into two flat layers without any appreciable hollow space
between them. Spore-ball, or spore-cake enclosed in a common membrane, one spore-cake being the product of each plasmodium. Spores
H
(2) Blomfield, J. E. and Schwartz, E. J. Some observations on the tumours on Veronica
Chamædrys caused by Sorosphæra veronica Ann. Bot. Vol. 24. Pp. 34-43· 1910.
(3) Maire, R. and Tison, A. "La cytology des Plasmodiophoracées et la classe des Phytomyxina”
Ann. Mycol. Vol. 7. Pp. 226-253. 1909.
Supplement No. 1, 1932.
119
No comments yet.
Private notes are available after approval.