The seedcoat of white fir is thinner than that of red fir and contains more vesicles, the number varying between 5 and 12/seed, although 7 to 9 are more common (Kitzmiller and others 1975). About 20% of the fresh weight of European silver fir seeds is resin (Cermak 1987), 90 to 95% of which is monoterpene hydrocarbons (principally limonene) (Cermak 1987; Cermak and Penka 1979; Penka and others 1977).