. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Uredospores and a teleuto- spore (/) of wheat rust.— De Bary, spots are caused by collections of spores of the rust. The mycelium of the plant is within the blade of the leaf, where it takes its food supply from the living cells of the green leaf. The mycelium sends up stalks through the stomata of the leaf ; it is these that hold the sporangia, filled with myriads of yellow-brown spores. The spores produced in the summer time are thin-walled and easily blown by the wind; wherever they alig
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. Uredospores and a teleuto- spore (/) of wheat rust.— De Bary, spots are caused by collections of spores of the rust. The mycelium of the plant is within the blade of the leaf, where it takes its food supply from the living cells of the green leaf. The mycelium sends up stalks through the stomata of the leaf ; it is these that hold the sporangia, filled with myriads of yellow-brown spores. The spores produced in the summer time are thin-walled and easily blown by the wind; wherever they alight on a wheat plant, there they germinate to form another mass of hyphse within the leaf. These parasites again produce more of the uredo- spores, as the summer spores are called. In the early fall the rust, instead of forming thin-walled spores, produces a curious, double, thick- walled spore in its place. This spore, known as a te- leutospore, remains dormant during the winter. In the early spring it germinates wherever it happens to have fallen, as it is not at this stage a true parasite. Upon germination it forms a threadlike body. On this body are formed tiny sporelike structures which have been named sporidia. The spo- ridia germinate only upon the barberry, where they form a mycelium within the leaf. This mycelium soon forms little masses of spore cases which, because of their appearance, are called cluster cups. The cluster cups may easily be seen with the naked eye on the surface of the infected barberry leaf. Spores from the cluster cups are carried by the wind to a neighboring wheat field, and there germinate upon the blade of wheat, to form the parasite we have already called wheat rust. In some cases the cluster-cup stage appears to be left out of the life cycle, the sporidia germinating directly upon the wheat plants. Teleutospore germi- nating and form- ing sporidia, s, s. (From Coulter, Plant Structures.). Section through a cluster cup of wheat rust in the lea
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