. The American florist : a weekly journal for the trade. Floriculture; Florists. Kig. 1. A rose leaf, upon the surface of which are spots of the fungus, Actinonema rosic. A, tlic fungus as it appears in its early stage.— It grows rapidly spreading into the surrounding tissue in a dendritic man- ner, until the greater part of the leaf has become infested. A pale yellow zone surrounds the spot, and as the fungus develops, the zone increases, until all that part of the leaf not occupied by the fungus has assumed the yellow tinge. I'pon making a vertical section of the leaf and placing it under hi
. The American florist : a weekly journal for the trade. Floriculture; Florists. Kig. 1. A rose leaf, upon the surface of which are spots of the fungus, Actinonema rosic. A, tlic fungus as it appears in its early stage.— It grows rapidly spreading into the surrounding tissue in a dendritic man- ner, until the greater part of the leaf has become infested. A pale yellow zone surrounds the spot, and as the fungus develops, the zone increases, until all that part of the leaf not occupied by the fungus has assumed the yellow tinge. I'pon making a vertical section of the leaf and placing it under high magnify- ing power, much may be ascertained con- cerning the true nature of the The fungus is found to lie upon the •pidermis, immediately underneath the cuticle. The mycelium of the young plant, by rapid growth, forms a stratum or layer in this part of the leaf. At various points in this stratum, the spores or reproductive bodies are developed from the mycelium. They push upward in a mass against the cuticle, which soon bursts and rolls back, forming a minute ragged cup, as in Fig. 2. Many of these minute cups upon the blackened surface of the leaf causes it to present a rough- ened Fig. 2. Vertical section of a rose leaf, sup- porting the "black ; passing through a nest or cup of spores, .-i, upper epidermal cells filled with a dark brown granular substance.— X360, Orixiinil, Shortly after reaching the surface, the spores become detached and are trans- ported by the wind or other agents, to neighboring rose leaves where they soon germinate, and thus the disease is rap- idly spread. The spores are very minute in their structure, appearing to the naked eye as dust particles. Magnified five or six hundred diameters they are shown to be oblong bodies, constricted in the mid- dle, and are divided into two cells by a transverse partition. Fig. 3 represents these spores as they appear under the microscope. From the layer of mycelium, ly
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectfloriculture, bookyea
