The white spruce (Picea alba), sometimes met with in English plantations, is a tree of lighter growth than the black spruce, the branches being more widely apart; the foliage is of a light glaucous green; the small light-brown cones are more slender and tapering than in P. nigra, and the scales have even edges.
Correlated with their life in dry situations, the bulk of the tissue is succulent, forming a water-store, which is protected from loss by evaporation by a thickly cuticularized epidermis covered with a waxy secretion which gives a glaucous appearance to the plant.
In diameter, and weighing more than 4 lb); the scales end in long hooked points curving upwards; the leaves are long, rigid, and glaucous in hue.
The Scotch fir is a very variable tree, and certain varieties have acquired a higher reputation for the qualities of their timber than others; among those most prized by foresters is the one called the Braemar pine, the remaining fragments of the great wood in the Braemar district being chiefly composed of this kind; it is mainly distinguished by its shorter and more glaucous leaves and ovoid cones with blunt recurved spines, and especially by the early horizontal growth of its ultimately drooping boughs; of all varieties this is the most picturesque.
As a picturesque tree, for park and ornamental plantation, it is among the best of the conifers, its colour and form contrasting yet harmonizing with the olive green and rounded outline of oaks and beeches, or with the red trunk and glaucous foliage of the pine.
The absence of the ordinary bright green colours of vegetation is another peculiarity of this flora, almost all the plants having glaucous or whitened stems. Foliage is reduced to a minimum, the moisture of the plant being stored up in massive or fleshy stems against the long-continued drought.
The leaves are glaucous and smooth like those of a swede turnip. For a seed-crop rape is sown in July or early August in order that the plants may be strong enough to pass the winter uninjured.
As at Walden, in sultry dog-day weather, looking down through the woods on some of its bays which are not so deep but that the reflection from the bottom tinges them, its waters are of a misty bluish-green or glaucous color.
Instead of the white lily, which requires mud, or the common sweet flag, the blue flag (Iris versicolor) grows thinly in the pure water, rising from the stony bottom all around the shore, where it is visited by hummingbirds in June; and the color both of its bluish blades and its flowers and especially their reflections, is in singular harmony with the glaucous water.
P. Ayacahuite, the common white pine of Mexico, spreads southwards on to the mountains of Guatemala, it is a large tree with glaucous foliage like P. Strobus, and yields a valuable resin.