Briancon manna is met with on the leaves of the common Larch, and bide-khecht on those of the willow, Salix fragilis; and a kind of manna was at one time obtained from the cedar.
In all three zones occur the chestnut, aspen, willow (especially Salix laurea), hornbeam, birch, alder, juniper and yew; while the mountain ash, hazel, wild plum, wild pear and other wild fruit trees are found at rarer intervals.
Thus the galls of Cynips and its allies are inhabited by members of other cynipideous genera, as Synergus, Amblynotus and Synophrus; and the pine-cone-like gall of Salix strobiloides, as Walsh has shown, 2 is made by a large species of Cecidomyia, which inhabits the heart of the mass, the numerous smaller cecidomyidous larvae in its outer part being mere inquilines.
Thus the characteristics of the currant-gall of Spathegaster baccarum, L., which occurs alike on the leaves and on the flower-stalks of the oak, are obviously due to the act of oviposition, and not to the functions of the parts producing it; the bright red galls of the saw-fly Nematus gallicola are found on four different species of willow, Salix fragilis, S.
Aces plants of the reed swamp, and includes such trees as the alder Ilnus rotundifolia), willows (e.g., Salix alba, S.
And Reid has shown that during the glacial period the existing flora was replaced by an arctic one represented by such plants as Salix polaris, S.
The chief species in cultivation are: Salix viminalis (the common osier) and S.
A American beetle, Saperda inornata (Cerambycidae), which forms the pseudo-galls of Salix longifolia and Populus angulata, or cottonwood.
This was not confined to the north but may occur on the mountains of England and Wales: Salix herbacea, Silene acaulis and Dryas octopetala will serve as examples.
The genera best represented are Ficus (21 species), Quercus (16 species), Populus (ir species), Rhamnus (9 species), Platanus (8 species), Viburnum (7 species), Magnolia (6 species), Cornus (5 species), Cinnamomum (5 species), Juglans (4 species), Acer (4 species), Salix (4 species), Aralia (3 species), Rhus (3 species), Sequoia (3 species).