The Norway spruce has been propagated more extensively as yet than any other species, and has been widely planted in the Eastern and prairie States. But it is now losing its popularity. As the trees attain the age of thirty years at the East they become relatively thin, and in the West they begin to fail in twenty years. At this time the first-planted trees west of Chicago are dead or in a low state of vitality. This is equally true of its nursery varieties. Yet the Norway is rapid in growth, and for a number of years it shows thrift and beauty as lawn specimens or as shelters and wind-breaks. The White spruce is a Northern species, and varies in hardiness and longevity. As obtained from the Black Hills in South Dakota, it is a beautiful and long-lived tree over the prairie States, and will probably sustain its record east to the Atlantic. But it seems to be a long-lived tree as obtained nearer the lakes. At Wankegan, Illinois, trees planted over fifty years ago are still dense in habit, regular in form, and are well branched to the ground. These trees are still making an annual growth. As obtained near Chippewa Falls, Wisconsin, a large per cent of the plants have the blue tinge of color of Picea pungens.
The silver spruce (Picea pungens) comes to us from the eastern slopes of the Rocky Mountains. We also have some old trees of this beautiful species, brought to the prairies during the Pike's Peak gold excitement many years ago. These old trees seem to show added beauty each year. Those that had little show of color when young now are nearly as silvery as those that were the favorites when small. This grand species also seems to do well nearly across the continent. The common name "blue spruce " is not expressive, and properly belongs to the caerulea variety of the white spruce grown in French nurseries. Silver spruce is far better, as the finest specimens have a silvery-blue expression, especially as grown in the dry air of the West. (Fig. 94.)
Fig. 94. - Colorado silver spruce (Picea pungens). (After Maynard.)
The Engelmann spruce (Picea Engelmanni) is another noble species of eastern Colorado. It is a slower growerthan pungens, but it has finer foliage and is more compact in habit. Its ability to stand the dry air of the prairies seems to depend on the locality whence the plants come. Plants from the Clear Creek Valley of Colorado have stood in Iowa as well as the Black Hills spruce. This species is often mixed with Picea pungens in gathering seed in Colorado, and also in digging young plants ; but in reality it more nearly resembles the white than it does the silver spruce.
In Eastern and Southern nurseries are to be found several varieties and species of the spruce of local value, such as the Alcock from Japan, the Smith from the Himalayan Mountains, the Oriental from Asia and east Europe, and numerous varieties of the Norway that will give variety of expression.