The Geography of Phytochemical Races

5.2 Nonvascular Plants 227
compounds new to the species were also reported: E- and Z-isomers (N.B., trans and
cis, respectively) of (+)-bornyl p-coumarate [423 is the E-form], and the E-isomer of
(+)-bornyl ferulate [424]. These compounds appear to be restricted to chemotypes
I and II. Chemotype I is the most widely distributed, whereas chemotype II tends
to be coastal. Chemotype III is restricted to forests in mountainous regions. It is
interesting to note that a collection of C. conicum corresponding to chemotype
III has also been reported from North America (Illinois) (Wood et al., 1996).
It was also reported in that paper that specimens from northwestern California
(near Humboldt) did not exhibit any trace of methyl p-cinnamate.
Additional information on terpene-based chemotypes of C. conicum comes
from a recent paper by Melching and König (1999), who studied plant material
collected in southern Germany (Adelberg, near Göppingen). Major components
of the essential oil fraction, illustrated in Fig. 5.5, were shown to be
the known (−)-selin-11-en-4-ol [425] and conocephalenol [426]. The latter
compound was fi rst isolated from C. conicum collected in Scotland, and later
found in a sample of the plant from Germany (Asakawa, 1995). In the newer
work, three novel brasilane-type sesquiterpenes were identifi ed: brasila-5.10diene
[427], brasila-5(10),6-diene [428], and brasila-1(6),5(10)-diene [429]. The
compounds present were presilphiperfolan-1-ol [430], the aromatic compound
3,4-dimethoxyphenylstyrene [431], and a number of other nonsesquiterpene
derivatives. The presence of the styrene derivative is interesting, insofar as it has
Fig. 5.5 Compounds 425–433, essential-oil components from Conocephalum conicum