The Secretary of Agriculture is authorized and directed to cause such shade, ornamental, fruit, and shelter-belt trees, shrubs, vines, and vegetables as are adapted to the conditions and needs of the semi-arid or dry-land regions of the United States, to be propagated at an experiment station of the Department of Agriculture to be established at or near Cheyenne, Wyoming, and seedlings and cuttings and seeds of such trees, shrubs, vines, and vegetables to be distributed free of charge under such regulations as he may prescribe for experimental and demonstration purposes within the semi-arid or dry-land regions of the United States.