The Geography of Phytochemical Races

262 6 Oceanic Islands
preparation of a daily beverage, occurs on Vanuatu and Wallis; chemotype H, which,
incidentally, is described as the most palatable, occurs only in Vanuatu and Western
Samoa; and chemotype I is not only grown mainly in Fiji, but also occurs on Tonga,
Samoa, the Cook Islands, Tahiti, the Hawaiian Islands, and Pohnpei. Chemotypes
E–I all represent P. methysticum. Despite the complexity of this system, not in the
least surprising in view of the migration history of humankind in the area, signifi cant
patterns of distribution of secondary metabolites emerged from a combination of
quantitative methods (HPLC) and multivariate statistical analysis. There is no question
that this is labor-intensive work, but the results, as was also seen in studies of
conifer terpenes described earlier in the review, are clearly worth the effort.
Two recent papers might be of interest to workers dealing with kavalactones.
Dharmaratne et al. (2002) describe chromatographic and spectroscopic data for 13
of the more common kavalactone derivatives. Siméoni and Lebot (2002) attempted
to identify factors responsible for kavalactone content and chemotype using plants
under cultivation on several islands of Vanuatu. The content of kavalactone appears
to be determined primarily by the local environment or by the agricultural methods
used by local farmers. Growth studies over a period of several years showed that
10-month-old juvenile plants accumulate about 3% (dry weight) of kavalactone
with the concentration rising to 8% after 18 months. At this age the concentration
seems, for the most part, to stabilize.
6.3.2 Degeneria (Degeneriaceae)
The Fiji Archipelago lies astride longitude 180°E/W (between ca. 177°E and ca.
179°W) and between ca. 16° and 19° S latitude in the southern Pacifi c Ocean. The
archipelago consists of two main islands, Viti Levu and, to the northeast, Vanua
Levu, along with many smaller islands, islets, and reefs (Fig. 6.7). The plants of
interest belong to the genus Degeneria, which, until a few years ago, was thought to
consist of the single species D. vitiensis I.W. Bailey & A.C. Smith (I. W. Bailey and
Smith, 1942). Based upon extensive reinvestigation of Degeneria on the islands,
Miller (1988) defi ned a second species D. roseifl ora J. M. Miller, based upon several
morphological features and a distinct fl oral pigmentation, as indicated by the
new taxon’s name. Although no chemical analyses were performed on fl oral tissue
of the new species, it seems reasonable to suggest that the presence of anthocyanin
pigments can be credited as a chemical distinction between the two species.
The distribution of the two species is of interest insofar as they appear to be more
or less restricted in occurrence: D. vitiensis occurs on Viti Levu, whereas D. roseifl ora
occurs on Vanua Levu and adjacent Taveuni. Both species occur on older substrates
on the larger islands, whereas D. roseifl ora is found on younger substrates on
Taveuni. A. C. Smith (1981, 1985) thought that its occurrence on the smaller island
might have been the result of short-distance dispersal via birds or bats.
According to Takhtajan (1969) and Cronquist (1981) Degeneriaceae represents
an ancient lineage within the Magnoliales. The “old enigma” referred to by