The Geography of Phytochemical Races

118 2 Examples Within Continents
Table 2.21 Distribution of kaempferol and quercetin glycosides in Cnidoscolus spinosus (after
Kolterman et al., 1970)
Population No. b Kaempferol glycosides Q-Glysa GAL GLC RHM RGR RUT RHM RUT
Northwestern 3 0c 0 3 3 3 1 0
Central 3 2 2 1 2 2 1 1
Southeastern 2 0 0 0 2 0 1 2
a Q = quercetin; Glys = glycosides; GAL = galactoside; GLC = glucoside; RHM = rhamnoside;
RGR = 3-O-rhamnosylgalactoside; RUT = rutinoside.
b Number of populations sampled.
c Number of populations exhibiting the compound.
in the middle of the range possessed all of the compounds observed in the species,
with reduction in numbers in both the southeastern and northwestern populations.
The authors suggested that range expansion in both directions from ancestral populations
in the middle of the present distribution could account for the observed profi les.
Sample size is a problem in this study, as noted by the authors.
2.7.22 Cupressus (Cupressaceae)
Zavarin et al. (1967b) described the occurrence of tropolone derivatives, sevenmembered
ring compounds, in species representing both the Old World and New
World members of Cupressus, the true cypresses. Owing to the diffi culty of acquiring
samples of these heartwood constituents, coupled with diffi culties in purifi cation
and analysis, sampling was very limited. Nonetheless, suffi cient differences
between populations were noted to suggest that a wider sampling using more conservative
sampling methods, allied with more sensitive analytical techniques, might
provide useful insights into relationships within the genus. Two examples serve
to illustrate the variety of structures involved, and hence biosynthetic step differences
between populations. Cupressus sargentii Jepson occurs from Santa Barbara
County in the south to Mendocino County in the north (Fig. 2.74) and is felt by
some workers to exist in two forms, one coastal and one from inland. The inland
form was shown to accumulate four compounds, nootkatin [237] as a major component
(see Fig. 2.75 for structures 237–241), β-thujaplicin [238] and β-thujaplicinol
[239] as lesser components, and β-dolabrin [240] as a trace component. The coastal
form exhibited the simpler profi le, in that it lacks β-thujaplicinol and β-dolabrin.
The two forms share the capacity to make both the basic terpene-derived tropolones,
as well as the sesquiterpene-derived tropolone nootkatin, but differ in the oxidation
level of the tropolone ring.
Two collections of C. arizonica Greene also exhibited differences involving the
same set of compounds: a sample from Mexico afforded β-thujaplicin as a minor
component and nootkatin, whereas a specimen from the Chiricahua Mountains in