Some Caryophyllaceous Plants Influenced in Growth and Structure by Artificial Illumination Supplemental to Daylight

Abstract

1. Eight species of Caryophyllaceous plants were grown from seed to maturity in the greenhouse, the natural daylight being supplemented by continuous electric light from incandescent bulbs furnishing 10-20 foot-candles. 2. The experimental plants grew taller than the controls, blossomed earlier, often had more slender stems with the vascular tissue, especially the phloem, weakly developed. Roots tended to be small and short; starch was generally absent from pith and cortex of the stem. Leaves were sometimes but not always thinner than those of the controls, and sometimes showed a single layer of palisade as in rather typical shade plants. 3. Certain species of Agrostemma, Dianthus, and Viscaria were brought into bloom very quickly, even during short winter days, by the use of continuous supplementary light.