Phytochrome has been shown to be involved in the germination of seeds of a number of pine species as determined by the responses of these seeds to red and far-red irradiations (4, 7, 9). Nyman ,(7) found that even before imibibition, germination of Pinus silvestris seeds can be promoted by red irradiation. McLemore (5) found that germination of longleaf pine seed (P. palustris) can be repeatedly promoted and inhibited by short exposures to red and far-red light, after imbibition. This species has relatively large embryos which can be easily isolated. Therefore, it was of interest to see whether germination of P. palustris seeds could be affected early during imbibition by red and far-red light, and to investigate the phytochrome spectrophotometrically.