PRACTICAL ARBORICULTURE 175 
PLANTING SAND DUNES. 
The intimate relation of apparently insignificant objects with those of great 
inagnitude is often passed unobserved. The Yucca is neither a forest tree nor 
even a shrub, simply an herb. Yet we may find great forests successfully grown 
under the kindly shelter and protection afforded by this humble plant. 
There are two prominent forms of the Yucca, although others are weil known. 
The Adams thread and needle of the gardens throughout the eastern portion of 
America, Yucca fillimentosa, and the western variety, Yucca glauca, which we 
illustrate, a dweller of the arid deserts and lower mountains of the mid-continent. 
Both sorts have very large, fleshy roots, which penetrate the soil to consider- 
able depth for the purpose of collecting and storing water for a long period of 
drouth. 
On the mesas of Colorado, in graveliy locations, the Yucca is almost the only 
herb which can survive the prolonged drouths of this region. 
On account of the strong, deep roots, and stored energy of this plant, it is 
enabled to push upward through a heavy covering of sand, and for this reason 
the Yucca would be a desirable plant to use upon the vast sand dunes of sea and 
lake coast to fix the sands which are constantly moved by heavy winds in unpro- 
tected localities. 
The list of trees and plants which will grow under the prevailing conditions 
ef ocean and lake shores, where constant winds build these mountains of sand and 
roll them along inland, is a very short one, since the sand buries seeds and small 
plants too deep for them to push through. 
The first object to be accomplished is the elevation of the wind current a few 
inches above the surface so that it cannot pick up the grains of sand. Beach 
grasses of several varieties are commonly used for this purpose. But these will, 
in time, be covered up unless larger shrubs and trees can be started into growth 
and supported for at least one season, and these grown quite thickly, say 8 by 8 feet. 
It is probable that the western Yucca will accomplish this object, perhaps in 
combination with the beach grass, better than by the grass alone. 
Unlimited quantities of the seeds may be secured on the western mesas. This 
should be grown in nurseries a vear and transplanted in the sands either 4 by 4 
feet or 8 by 8 feet, with grass intermediate. ; 
At the same time one or two year trees should be planted among the herbace- 
ous plants at the rate of 500 to 700 per acre. 
The Yucca is abundant in western Kansas and Nebraska, and if advantage 
was taken of its presence to plant hardy trees and shrubs, either the small plants 
