Various alpine species belonging to quite distinct families form close moss-like cushions, gemmed with star-like flowers, or covered completely with a carpet of blossom. On the lower mountain slopes and in alpine valleys trees seem to flourish with peculiar luxuriance. Pines and Firs and Larches above; then, as we descend, Beeches and magnificent Chestnuts, which seem to rejoice in the sweet, fresh air and the pure mountain streams. To any one accustomed to the rich bird life of English woods and hedgerows, it must be admitted that Swiss woods and Alps seem rather lonely and deserted. Still the Hawk, or even Eagle, soaring high up in the air, the weird cry of the Marmot, and the knowledge that, even if one cannot see Chamois, they may all the time be looking down on us, give the Alps, from this point of view also, a special interest of their own. Another great charm of mountain districts is the richness of colour. "Consider,[38] first, the difference produced in the whole tone of landscape colour by the introductions of purple, violet, and deep ultra-marine blue which we owe to mountains. In an ordinary lowland landscape we have the blue of the sky; the green of the grass, which I will suppose (and this is an unnecessary concession to the lowlands) entirely fresh and bright; the green of trees; and certain elements of purple, far more rich and beautiful than we generally should think, in their bark and shadows (bare hedges and thickets, or tops of trees, in subdued afternoon sunshine, are nearly perfect purple and of an exquisite tone), as well as in ploughed fields, and dark ground in general. But among mountains, in addition to all this, large unbroken spaces of pure violet and purple are introduced in their distances; and even near, by films of cloud passing over the darkness of ravines or forests, blues are produced of the most subtle tenderness; these azures and purples passing into rose colour of otherwise wholly unattainable delicacy among the upper summits, the blue of the sky being at the same time purer and deeper than in the plains. Nay, in some sense, a person who has never seen the rose colour of the rays of dawn crossing a blue mountain twelve or fifteen miles away can hardly be said to know what tenderness in colour means at all; bright tenderness he may, indeed, see in the sky or in a flower, but this grave tenderness of the far-away hill-purples he cannot conceive."