Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplants00tube Year: 1897 384 UREDINEAE. spores grow on needles and twigs of Coniterae, the aecidia on the leaves of various liosaceae (Pomaceae). Five species occur in Germany, but there are many in America. Gymnosporangium clavariaeforme Jacquin. (Britain and Anu-rica.) Tlie mycelium of this species perennates in twigs of Juniperus communis. Infection is brought about by aecidiospores. In the following year a swelling
Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplants00tube Year: 1897 384 UREDINEAE. spores grow on needles and twigs of Coniterae, the aecidia on the leaves of various liosaceae (Pomaceae). Five species occur in Germany, but there are many in America. Gymnosporangium clavariaeforme Jacquin. (Britain and Anu-rica.) Tlie mycelium of this species perennates in twigs of Juniperus communis. Infection is brought about by aecidiospores. In the following year a swelling of attacked places is evident, and this increases till death of the host ensues. In spring, about the beginning of April, little light- yellow cone-like structures break out on the swollen places, f' Fig. 217.—Section through a swelling on a sixteen-year twig of Juniper attacked by Gymnosporangium in its eighth year; three conical spore-cushions are indicated, also a cushion-scar with the scar-tissue. (After Woemle.) Fig. -ils. —Lmigitudiual section of a spore-cushion of Gymnosporanqhnn eld- vnriitcforme. Somewhat diagrammatic. (After Woernle.) and during rain swell up into long club-shaped sporophores, containing long-stalked, spindle-shaped teleutospores, some thick- coated, some thin. The sporophores swell and ultimately form a common mass in which the teleutospores germinate. The spores have four germ-pores, each capable of giving off a promyceliuin with pointed sterigmata producing sporidia, which are cast loose and distributed by wind. Germination of sporidia takes place on leaves, cotyledons, petioles, and shoots of various Pomaceae, where they may induce swellings or curvature, often to a considerable extent.
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