Repository: UIHistories Project: Board of Trustees Minutes - 1884 [PAGE 132]

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136 The species of this genus are difficult to determine morphologically one from another, and comparatively little has been done towards elucidating life histories through cultures. It is supposed that Colesporium senecionis and Peridermium pini are alternate forms of one species, but other eecidial states are unknown. The so-called uredospores are produced in chains and according to the adopted classification, would by themselves fall in the genus Cceoma. The query arises as to whether this should be looked upon as the aecidium or uredo stage. So far as observed, this form grows on the same leaf and usually just before the teleutoform, characteristics of the latter rather than the former. If indeed Peridermium pini is the aecidium form of Coleosporium senecionis, then the pulverulent spores on Senecio, one would say, must be the uredo form, and these are very similar to the first formed spores of the other species. C. sonchi-arvensis, (Pers.) Lev. II and III. Hypogenous, rarely epiphyllous; uredosori scattered or united in groups, often very numerous and sometimes crowded or confluent, elliptical or irregular, powdery; uredospores elliptical, often irregular, thickly studded with little obtuse tubercules, orangeyellow, but soon fading, 15-21 by 19-24 ,a; teleutoson scattered or united in groups, often very numerous and sometimes confluent, low, at first orange-yellow, changing to pale reddish-brown; teleutospores about four-celled, cylindrical or enlarged above; epispore thin, smooth. On leaves of Vernonia fasciculata; Elephantopus Carolinianus; Aster sagittifoliiis; Aster sps.; Solidago latifolia; S. altissima; S. ulmifolia; S. Canadensis; 8. gigantea; Solidago sps.; Silphium integrifolium and 8. terebinthinaceum. The name adopted is from Uredo sonchi-arvensis, Pers. For the fungi here included many names have been proposed under the idea of specific distinctness., But whatever differences exist seem to be so connected by intermediate forms that those upon the host-plants named are considered specifically identical. There is therefore included such as have been named, Uredo solidaginis Schw., U. terebinthinaceum, Schw., Coliosporiam compositarum, Lev., Uredo or Cceoma elephantopsidis, Schw., Coleosporium. vernonia B. & C. and C. solidaginis, Thiim. Perhaps the form on Vernonia differs more than others from the type on account of the uredospores being smaller and the teleutospores being more enlarged above. On Elephantopus the teleutosori are grouped in circles. C. ipomoece, (Schw.) II and III. Hypophyllous; spores yellowish or none; sori minute, scattered or irregularly clustered, circular. II. Uredo spores irregularly oval, strongly echinulate, 18 by 26 ,a. III. Sori convex, deep reddish-orange; spores (chains) oblong or slightly clavate, conspicuously 4-6 septate, about 10 by 26 //, segments widest transversely. On leaves of Ipomoea nil; I. lacumosa; I. pandurata; (Uredo ipomoece, Schw.)