Anatomical Study of Plants Grown Under Glasses Transmitting Light of Various Ranges of Wave Lengths

Abstract

On the bases of vascular development; diam. and height of stem; thickness and differentiation of leaf; and development of roots; sunflower, soybean, and four-o''clock plants grown in an outdoors situation are 1st in place, those under glass allowing transmission of all the spectrum 2nd, and those with only the rays of the visible spectrum 3rd. The weakest development occurs where the rays are restricted chiefly to red or to blue, while an intermediate degree of development occurs in plants in shade and under glass where violet and part of the blue rays are lacking. Similar intensities in the full-spectrum and visible-spectrum houses indicate that quality determines the difference. In the other houses, both quality and intensity may be effective in bringing about changes.