Seed Persistence: A Correlation Between Seed Longevity in the Soil and Ortho-Dihydroxyphenol Concentration

1. Ortho-dihydroxyphenol and cyanoglycoside concentrations were determined in seeds of over 80 species, drawn largely from the native British flora but including a number of weeds and other species of agricultural significance. 2. All seeds examined contained at least trace amounts of hydroxyphenols and three-quarters released hydrogen cyanide on hydrolysis. A highly significant correlation was found between (a) seed persistence in the soil and ortho-dihydroxyphenol concentration and (b) between protein content, as a measure of the nutritional value of the seed, and ortho-dihydroxyphenol content. No such relation was found with cyanoglycosides. 3. Particularly high concentrations of ortho-dihydroxyphenols were found throughout species within the order Myrtales (Onagraceae and relatives), all with little or no seed endosperm. 4. From this broad survey we conclude that ortho-dihydroxyphenols, as a class, play an important role in maintaining seed persistence in the soil, probably by deferring or decreasing the rate of decomposition by microbes as well as by defending against herbivory, and that this is one important mechanism, along with morphological adaptations, which confers longevity and persistence on seeds buried in cool temperate and relatively moist soil conditions.