Page:Tree Crops; A Permanent Agriculture (1929).pdf/329

 FIG. 110. Top. Majorca. Heavy trees in the foreground, grafted oaks; feathery trees, almonds. The heavy trees on the steep hill at the back are oak (ilex), thinned out to make acorns for hog-fattening—FIG. 111. Center. An Appalachian valley in Central Pennsylvania. The steepness of the hillside field is submitted as evidence of widespread agricultural insanity—F1G. 112. Bottom. A grove of locusts (Robinia Pseudacacia) whose nitrogenous roots support a good stand of bluegrass on a shaly Allegheny Bodie in Central Pennsylvania where grass is rare. (Photos J. Russell Smith.)