The gymnosperms area monophyletic yet diverse group of woody trees with app
rox. 730 extant species in 17 families. A recent survey showed that DNA C-v
alues were available for approx. 16 % of species, but for only 12 of the 17
families. This paper completes Familial representation reporting first C-v
alues for the five remaining families Boweniaceae, Stangeriaceae, Welwitsch
iaceae, Cephalotaxaceae and Sciadopityaceae, C-values for nine Ephedra and
two Gnetum species are also reported. C-values are now available for 152 (2
1 %) species. Analysis confirins that gymnosperms are characterized by larg
er C-values than angiosperms (modal IC of gymnosperms = 15.8 pg compared wi
th 0.6 pg in angiosperms) although the range (IC = 2.25-32-20 pg) is smalle
r than that in angiosperms (IC = 0.05-127.4 pg). Given complete familial co
verage for C-values and increasing consensus in gymnosperm phylogeny, the p
hylogenetic component of C-value variation was also investigated by compari
ng the two datasets. This analysis revealed that ancestral gymnosperms (rep
resented by cycads and/or Ginkgo; mean genome size = 14-71 pg) probably had
larger genomes than ancestral angiosperms. (C) 2001 Annals of Botany Compa
ny.