The Geography of Phytochemical Races

2.7 North and Central America 105
confi rmed the visual comparisons. The mass of information generated by the HPLC
analyses was subjected to multivariate statistical analysis. Principal- components
analysis revealed a large degree of dispersion in the data, with orientin dominating
axis I (axis I accounted for 72% of total variation), isoörientin [213, R 1 = glucose,
R 2 = hydrogen] dominating axis II (12%), and orientin 3′-O-glucoside [214] dominating
axis III (10%). Despite the large contribution from orientin, no clear-cut
grouping of populations appeared to exist in most of the northern and central
parts of the range. The southernmost populations are more discernible than those
throughout the rest of the range, but the major outcome of these analyses was
recognition of clinal variation in a north–south axis, with the high-orientin plants
originating from the southernmost populations. This agrees well with an observation
made by Fleak (1971) on plants from the southern populations, which consistently
display heavy anthocyanin pigmentation in the lower part of the stems. Stem
pigmentation was suffi ciently variable in plants from the rest of the range of the
species that Fleak and Dunn (1971) recognized the southern plants as L. sericeus
subsp. huffmanii. Accumulation of high concentrations of orientin in these individuals
provided support for their view. Flavonoid data provide no support, however,
for three other subspecies defi ned by Fleak (1971).
A resampling of populations, again representing the entire range of the species,
provided seed so that plants could be grown under controlled conditions of day
length and temperature. The fl avonoid fraction from each individual was then subjected
to HPLC analysis as before. Under uniform conditions, all quantitative differences
in the fl avonoid profi les disappeared! Further studies to determine what
environmental factor or factors is/are responsible for the quantitative differences in
orientin concentration in nature have not been undertaken. It is interesting to note
in passing that plants from the southern populations retained their red pigmentation
under the controlled conditions of the growth experiment, thus providing support
for the use of anthocyanic pigmentation as a character in suggesting subspecifi c
status for those individuals.
2.7.15 Satureja douglasii (Lamiaceae)
Terpene pattern variation has provided a useful means of investigating evolutionary
and ecological situations in a variety of plant groups. The next example, a study of
the monoterpenes of Satureja douglasii (Benth.) Briq. by Lincoln and Langenheim
(1976), is an excellent example of an investigation aimed at establishing possible
factors responsible for chemical variation exhibited by a species throughout its
range. Satureja douglasii occurs in a narrow band paralleling the coast from southern
British Columbia to southern California and disjunctly in a narrow band in the
western half of the Idaho panhandle and adjacent British Columbia. Sampling for
this study involved the coastal and near-coastal sites and constituted a north–south
transect between approximately 50°N and 34°N latitude (Fig. 2.67). (A specimen
from Idaho was analyzed but does not fi gure in the study.)