The Geography of Phytochemical Races

110 2 Examples Within Continents
Fig. 2.69 Compounds 221–224, fl avonoids of Pentagramma (Pityrogramma) triangularis. Compounds
225–228 from Encelia farinosa
Kaempferol methyl ether-bearing plants occur throughout the fern’s range,
whereas the ceroptene-pityrogrammin chemotype occurs from, roughly, central
California to the southern extent of the species in northwestern Baja California. Each
of these chemotypes consists of diploids and tetraploids that cannot be distinguished
on the basis of their exudate chemistry. An examination of the vacuolar components,
however, revealed the existence of fl avonol glycosides the presence of which
distinguished ploidy level within each exudate chemotype with only minor variation.
Thus, tetraploids of the ceroptene-pityrogrammin chemotype consistently exhibited
kaempferol 7-methyl ether 3-O-glucoside and 3-O-rhamnoglucoside as major
components. Diploid plants from two sites had the diglycoside in trace amounts.
Neither of these compounds was seen in plants belonging to the kaempferol methyl
ether exudate chemotype. A parallel situation exists with regard to the kaempferol
methyl ether exudate chemotype, wherein one sees quercetin 3-O-glucoside and
3-O-rhamnoglucoside in members of the tetraploid race but not in the diploid race.
One fi nal note on this topic involves an examination of diploid, triploid, and tetraploid
plants for their leaf exudate hydrocarbons (Seigler et al., 1975). n-Alkanes
having odd numbered chains from C 25 to C 33 were recorded for almost all plants
collected from several sites with much more limited distribution of hydrocarbons
based on C 35 and C 28 . The hydrocarbon data do not assist in distinguishing groups
within this species.