The antitumour activity of a foliage extract of a New Zealand gymnosperm, Libocedrus plumosa, against P388 leukaemia cells was due to β-peltatin 3. Deoxypodophyllotoxin 1 and β-peltatin A-methyl ether 2, P388-active lignans previously reported in L. bidwillii, were found at lower levels. High levels