The Geography of Phytochemical Races

12 2 Examples Within Continents
can be found from sea level to 2800 m in appropriate habitats. There have been suggestions
that it is most closely allied to taxa in the Mediterranean region. A recent
paper by Langlois et al. (2004) examined the alkaloid components of P. aculeatum
in an attempt to see if chemotaxonomic information might assist in pointing to relationships
within the genus, particularly with regard to sectional affi nities. The major
compound present in all parts of the plant was identifi ed as N-acetylanonaine [18.1,
Fig. 2.3], a noraporphine alkaloid not otherwise known in the genus, although members
of sect. Pilosa have yielded members of this group of compounds.
2.1.9 Ocimum gratissimum (Lamiaceae)
Ocimum gratissimum L., the tree basil, is a highly variable taxon with a center
of origin in Africa. Two subspecies have been recognized, subsp. gratissimum
and subsp. macrophyllum Briq., based upon stem, leaf, and infl orescence
characteristics, but levels of variation in these morphological traits are signifi cant.
In an effort to develop additional sources of data to address the problem, Vieira
et al. (2001) undertook a study of volatile components, fl avonoids, and random
amplifi ed polymorphic DNA (RAPD) markers. The number of samples used in
the study was small—only a dozen accessions—but the amount of variation in
both sets of secondary metabolites suggests that a detailed examination of a much
larger set representing the geographical range of the taxon, as well as cultivated
material, would repay the effort. Both qualitative and quantitative differences were
observed, which would allow detailed statistical analysis, an approach that the
reader will see below to have revealed signifi cant groupings in several taxa.
2.2 Australia and New Zealand
2.2.1 Chamelaucium uncinatum—The Geraldton Waxfl ower
(Myrtaceae)
Chamelaucium is a genus of a dozen species endemic to southwestern Australia.
The species under investigation here, C. uncinatum Schauer, occurs along the coast
from somewhat north of Perth (ca. 29°S) to north of Geraldton (ca. 27°30′S), over
a distance of approximately 350 km (Fig. 2.4). This species has provided several
cultivars for the cut-fl ower trade, where it is known as “waxfl ower” or “Geraldton
waxfl ower.” A recent study of the species sampled from its entire range demonstrated
the existence of clear-cut monoterpene races (Egerton-Warburton et al., 1998).
Leaf material representing 38 sites was collected from plants cultivated under
common garden conditions (University of Western Australia). Gas chromatographic
analysis of the leaf oil revealed 33 components, nine of which accounted for 80.5%