The discovery of the reversible red far-red control of plant growth and
development and the subsequent in vivo identification and isolation of
the photoreceptor pigment, phyto- chrome, constitutes one of the great
achievements in modern biology. It was primarily a group of
investigators at the Plant Industry Station, Beltsville, Mary- land,
headed by the botanist H.A. BORTHWICK and the physical chemist S.B.
HENDRICKS, who made the basic discoveries and developed a theoretical
framework on which the current progress in the field of phytochrome is
still largely based. While the earlier development of the phytochrome
concept has been covered by a num- ber of excellent articles by the
original investigators [104,105,33,238] as well as by others who
joined the field of phytochrome research later [72, 109, 219], a
comprehensive and up-to-date treatment of photomorphogenesis is not
available at present. Since it seems to be needed for teaching as well
as for researchers I have tried to summarize the present state of the
field, reviewing the historical aspects of the phytochrome story only
insofar as they are required to understand the present situation. The
emphasis of my treatment will be on developmental physiology
("photomorphogenesis") rather than on phytochrome per se.
