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.
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 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.
C. atlantica, the Atlas cedar, has shorter and denser leaves than C. Libani; the leaves are glaucous, sometimes of a silvery whiteness, and the cones smaller than in the other two forms; its wood also is hard, and more rapid in growth than is that of the ordinary cedar.
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.