The Geography of Phytochemical Races

212 4 Intercontinental Disjunctions
Table 4.7 Occurrence pattern of presumed enzymes in the biosynthesis of Euchresta flavonoids
(from Matsuura et al., 1994)
Taxon Origin Enzymes (correspond to names in Fig. 4.16)
1 2 3 4 5 6 7 8 9 10 11 12 13 14
E. japonica Japan + + + + + + + + + + + + +
E. formosana Taiwan, The + + + + + + + + + + +
Philippines
E. tubulosa China + + + + + + + + + + + +
E. longiracemosa China + + + + + + + + + + + +
E. horsfi eldii China + + + + +
E. horsfi eldii Thailand + + + + + + +
Sophora tonkinensis Outgroup + + + + + +
Fig. 4.17 Relationships among species of Euchresta
upon the idea, as argued by Stafford (1990), that C-glycosides represent a more
primitive character than O-glycosides. Thus, a high ratio of C- to O-glycosides
would indicate a taxon closer to the ancestral type. This analysis yielded results that
were in accord with the relationships suggested by the prenylfl avonoid phylogeny.
Matsuura et al. (1994) concluded from their analyses that E. horsfi eldii (not in
I.P.N.I. list) is the ancestral taxon in this genus (or is most closely related to the
ancestral taxon) and that the center of origin for the group is southeastern China.
From that area, the species migrated, with little in the way of morphological change,
into Thailand and then Indonesia. Radiation with accompanying morphological (and
chemical) diversifi cation occurred toward the east, which gave rise to the Philippine
taxon, and (generally) northward to yield the northern Chinese, Taiwanese, and
Japanese taxa.
4.5.2 Heterotropa ( = Asarum)(Aristolochiaceae)
N. Hayashi et al. (1984) described a study of phenylpropene derivatives in 44 species
of Heterotropa Morren & Dcne. growing in Japan. According to Mabberley
(1997, p. 339), Heterotropa is a synonym of Asarum L., which consists of some
70 North Temperate species, 30 of which occur in Japan. Regardless of the generic