The enzymes which act upon glucosides are many; the best known are emul sin and myrosin, which split up respectively amygdalin, the special glucoside of certain plants of the Rosaceae; and sinfgrin, which has a wide distribution among those of the Cruciferae.
The higher mountains rise abruptly from the plains; on their slopes, clothed below almost exclusively with the more tropical forms, a vegetation of a warm temperate character, chiefly evergreen, soon begins to prevail, comprising Magnoliaceae, Ternstroemiaceae, subtropical Rosaceae, rhododendron, oak, Ilex, Symplocos, Lauraceae, Pinus longifolia, with mountain forms of truly tropical orders, palms, Pandanus, Musa, Vitis, Vernonia, and many others.
The alpine rose (Rhododendron dauricum) clusters in masses on the higher mountains; juniper, spiraea, sorbus, the pseudo-acacia (Caragana sibirica and C. arborescens, C. jubata in some of the higher tracts), various Rosaceae - Potentilla fruticosa and Cotoneaster uniflora - the wild cherry (Prunus Padus), and many other shrubs occupy the spaces between the trees.
The Rosaceae are also abundantly represented, and among them are numerous species of the rose.
In the natural order Rosaceae, the series Querciflorae, and the very anomalous genus Casuarina and others, instead of a single macrospore a more or less extensive sporogenous tissue is formed, but only one cell proceeds to the formation of a functional female cell.