. Botany, an elementary text for schools. Botany. 184 STUDIES IN CRYPTOGAMS. 325. iori containing teleu- tospores of wheat true parasite, affecting wheat and a few other grasses. The mycelium here cannot be seen by the unaided eye, for it consists of threads whieli are present within the host plant, mostly in the intercellular spaces. These threads also send short branches, or haustoria (180), into the neighboring cells to absorb nutriment. The resting-spores of wheat rust are produced in late summer, when they may be found in black lines breaking through the epidermis of the wheat-stalk. They
. Botany, an elementary text for schools. Botany. 184 STUDIES IN CRYPTOGAMS. 325. iori containing teleu- tospores of wheat true parasite, affecting wheat and a few other grasses. The mycelium here cannot be seen by the unaided eye, for it consists of threads whieli are present within the host plant, mostly in the intercellular spaces. These threads also send short branches, or haustoria (180), into the neighboring cells to absorb nutriment. The resting-spores of wheat rust are produced in late summer, when they may be found in black lines breaking through the epidermis of the wheat-stalk. They are formed in masses, called sori (Fig. 325), from the ends of numerous crowded mycelial strands just beneath the epider- mis of the host. The individual spores are very small and can be well studied only with high powers of the microscope (X about 400). They are brown two- celled bodies with a thick wall (Fig. 326). Since they are the resting- or win- ter-spores, they are termed teleutospores ("completed spores")- They usually do not fall, but remain in the sori during winter. The following spring each cell of the teleutospore puts forth a rather stout thread, which does not grow more than sev- eral times the length of the spore and terminates in a blunt extremity (Fig. 327). This germ-tube, or hasklium, now becomes divided into four cells by cross-walls, which are formed from the top downwards. Each cell gives rise to a short, pointed branch which, in the course of a few hours, forms a single small spore at its summit. In Fig. 327 a germinating spore is drawn to show the basidium, h, divided into four cells, each producing a short branch with a little spore, s. A. most remarkable circumstance in the life-history of the wheat rust is the fact that the mycelium produced by the teleutospore can live only in barberry leaves, and it fol- lows that if no barberry bushes are in the neighborhood the teleutospores finally perish. Those which happen to lodge on a barberry bu
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
