. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 296 MAINTENANCE OF A FREE PASSAGE FOR AQUEOUS VAPOUR. over-arched by the neighbouring epidermal cells that a sort of vestibule is formed in front of the true pore. It can easily be imagined that drops of water which come to'such places are not able to press out the air from this vestibule, and there- fore cannot penetrate to the guard-cells of the stomata. In Hakea florida and Protect, mellifera, two Australian shrubs (see fig. 67), similar arrangements are met with, but here the stomata are still mo
. The natural history of plants, their forms, growth, reproduction, and distribution;. Botany. 296 MAINTENANCE OF A FREE PASSAGE FOR AQUEOUS VAPOUR. over-arched by the neighbouring epidermal cells that a sort of vestibule is formed in front of the true pore. It can easily be imagined that drops of water which come to'such places are not able to press out the air from this vestibule, and there- fore cannot penetrate to the guard-cells of the stomata. In Hakea florida and Protect, mellifera, two Australian shrubs (see fig. 67), similar arrangements are met with, but here the stomata are still more over-arched, so that they are only visible to anyone looking at the surface of the leaf through small holes at the top of the dome. The stomata on the green branches of various species of Ephedra are surrounded by mound-like projections from the cuticle of neighbouring epidermal «ells, and are at the same time somewhat sunken, so that an urn-shaped space is. Kg. 66. -Protection of Stomata from Moisture by Cutioular Pegs. i Vertical section of a Bamboo leaf; x 180. a Part of the lower portion of the section; x 460. » Part of the upper portion of the section; X460. formed above each stoma, from which water cannot dislodge the air. On the leaves of Dryandra floribunda, one of the Proteacese which grows in the thick Australian bush, several stomata occur at the bottom of small pits on the under side of the leaf, and from the side walls of the depression spring hair- like structures which interlace and form a loose felt-work, easily penetrated by gases but not by fluids (fig. 68). The stomata on the leaves of the Oleander {Neriwm Oleander) are similarly situated. These also are at the bottom of deep pits on the lower side of the leaf, and the entrance to them is beset with extremely delicate hair-like structures (see fig. 733). The oleander fringes the banks of streams in the sunny open country of Southern Europe and the East, and in its natural position it is most exposed to w
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1895
