. Fn, 162. - celia, may develop to inycelia; coalescence of coiiidia is unknown. In nutritive solutions conidia are formed in large numbers, and multiply yeast-like till nutriment fails. Ust. succisae Magn.^ frequents the anthers of Scabiosa Succisa, and forms pure white spores, easily distinguished from those of the two preceding species. The anthers appear to be thickly covered with glassy granules. The spores produce four-celled promycelia from which conidia are formed. (Britain.) Ust. tragopogonis (Pers.) (Britain). This fungus forms its spores in flowers of species of Tragopogon, and in m
. Fn, 162. - celia, may develop to inycelia; coalescence of coiiidia is unknown. In nutritive solutions conidia are formed in large numbers, and multiply yeast-like till nutriment fails. Ust. succisae Magn.^ frequents the anthers of Scabiosa Succisa, and forms pure white spores, easily distinguished from those of the two preceding species. The anthers appear to be thickly covered with glassy granules. The spores produce four-celled promycelia from which conidia are formed. (Britain.) Ust. tragopogonis (Pers.) (Britain). This fungus forms its spores in flowers of species of Tragopogon, and in many localities has a wide distribution. The development of the flower is retarded, so that it retains externally the appearance of a flower-bud en- closed in its bracts (Fig. 161). The dark-brown or violet spores escape through intervals between the bracts; they are 13-1 7m long, lO-lo/x broad, with reticulate markings on their coats. They easily produce in water four or five-celled promycelia from which conidia are given off, often followed by coalescence. In nutritive solutions development is much more vigorous, secondary conidia may be produced, and coalescence always takes place. Ust. scorzonerae (Alb. et Schwein.) is at first sight very similar to Ust. fragopogonis. Its spores are found in flowers of Scorzoneixt hmnilis, Sc. -purpurea, and cultivated species, Se. hispanica; while its mycelium hibernates in the perennial root-stocks of these. The spores are produced rapidly and in large numbers; they germinate easily in water, forming a four-celled promycelium, and thereafter conidia which do not pair. Ust. cardui Fisch. v. Waldh. (Britain). This is the cause of a stunting of the flower-heads of Carduus acanthoidcs, C. nutans, and Silyhnm Marianum, while at the same time they liecome filled with a l)rownish-violet spore-powder. The spores ' Magnus, Heduiijia, 1875. â Ustilago tragopogonis. Development of spores: successive stages of development, in order of the letter
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