. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. ENTIRE LEAVES AFFECTED BY FUNGI. 523 time the patch becomes a sunken, blistered hole from which resin flows; and every year the fructifications appear above the cortex in the form of numerous little cup-like structures which are white outside and scarlet-red in the concavity. As the disease progresses the infected patch gradually spreads, and infected trunks and branches can be easily distinguished at a distance, Towards the end of summer the needles on the twigs above the canker turn yellow, while t
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. ENTIRE LEAVES AFFECTED BY FUNGI. 523 time the patch becomes a sunken, blistered hole from which resin flows; and every year the fructifications appear above the cortex in the form of numerous little cup-like structures which are white outside and scarlet-red in the concavity. As the disease progresses the infected patch gradually spreads, and infected trunks and branches can be easily distinguished at a distance, Towards the end of summer the needles on the twigs above the canker turn yellow, while those on the healthy branches are still a beautiful green. This premature discoloration is a sure sign of the speedy death of the whole bough. A similar canker is produced on the. Fig. 358.—Various Galls iGall on the bract-scales o£ the pistillate flowers of the Gray Alder (Alnus incana) produced by Exoaseus Alni-incance. 2 Inflorescence of Valerimiella carinata. s The same inflorescence with galls produced by a gall-mite. * leaf rosette of the House-leek (Sempervivwm MHum).' « Leaf rosette of the same plant which has been attacked by the fungus Endo- phyllum Sempervivi and has become hypertrophied. Silver Fir (Abies pectinata) by ^cidium elatinum, but instead of being only on one side of the branch, as in the Larch, it forms a uniform swelling all round it. Cankers of this kind are produced by a Bacterial organism {Bacillus amylovorus) on fruit-trees (Apple, Pear, &c.), and on various trees belonging to the Amentiferae (Beeches, Hornbeams, Oaks, &c.) by the Fungus Nectria ditissima. When whole leaves undergo hypertrophy of the kind we have particularly remarkable changes of form. For example, the normal leaves forming the rosettes of the House-leek (Sempervivum hirtum; see fig. 358 *) are broadly obovate in form, being little more than twice as long as they are broad. The leaves of the same plant after they have been attacked by the parasitic Endophyllum Semper-. Pl
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
