VIABILITY AND DORMANCY IN SEEDS OF POLYGONUM AMPHIBIUM L., P. COCCINEUM MUHL. AND P. HYDROPIPEROIDES MICHX.

Abstract

THE IMPORTANCCE of amphibious species of Polygonum as food and cover for water-fowl and fish is generally recognized by wild life biologists. To these workers a knowledge of the behavior of the seeds is important when propagating these species. Some amphibious species are considered to be weeds under certain conditions and a knowledge of the behavior of their seeds is essential when they are to be controlled or eradicated. Various workers have reported conflicting results from laboratory germination tests and field plantings with seeds of amphibious species of Polygonum (Crocker, 1907; Fischer, 1907; Muenscher, 1936; Justice, 1941). In a previous study the author (Justice, 1941) (a) observed considerable variation in the response of different lots of seed of a given species of Polygonum, (b) obtained low percentages of germination in most tests in which seeds of the amphibious species were used, and (c) failed to confirm consistently the higher germination results by subsequent testing. For these reasons the investigation has been continued with seeds of Polygonum amphibium, P. coccineum and P. hydropiperoides. A few data reported herein have been taken from the previous paper by permission of the Director of the Cornell University Agricultural Experiment Station. These three species flourish and reproduce under amphibious conditions. It has been shown by several investigators that seeds of some lots of these species are dormant or exhibit delayed germination at maturity. In Polygonum the fruit is an achene and the presence of the pericarp might be expected to influence the physiological behavior of the seed during maturity, storage and germination. The pericarp is relatively thick and bony in P. amphibium and P. coccineum; in P. hydropiperoides it is hard but relatively thin. The pericarp may limit water absorption or exchange of gases or offer mechanical resistance to the germinating seed. The embryo is surrounded by an aleurone layer and lies outside a starchy endosperm in an angle of the seed (Woodcock, 1914). REVIEW OF LITERATURE.-Korsmo (1930) stated that Polygonum amphibium reproduces and spreads in western Europe both by seed and vegetative means, but that it rarely flowers or sets fruit on agricultural land. Fischer (1907) reported good germination from seed of this species along with results obtained from seed of several aquatic plants,