The Geography of Phytochemical Races

2.7 North and Central America 109
(See D. M. Smith, 1980, for a study of fl avonoid profi les of the varieties.) The overall
fl avonoid profi le of P. triangularis is fully in accord with the unique status of the species.
A detailed discussion of the chemistry of this system, which is beyond the scope
of the present treatment, can be found in a paper by Wollenweber and Dietz (1980).
An example of the complexity of fl avonoid biosynthesis in this species can be found
in a description of bifl avonoids present in the farinose exudate (Iinuma et al., 1994).
An early hint of the complexity of chemical variation lurking within this species
came from the work of Dale Smith and his colleagues at the University of
California at Santa Barbara (D. M. Smith et al., 1971). The group studied chromosome
numbers, spore size, and chromatographic profi les of plants obtained
from three populations in Santa Barbara County: Hoffman Hill, Painted Cave, and
Refugio Pass. Chemical differences among these populations were evident in the
different colors of the leaf exudates that characterize this species, yellow, white, or
green. Cytological study revealed diploids, triploids, and tetraploids based upon
x = 30. One-dimensional paper chromatograms sprayed with ferric chloride solution
revealed several spots, one of which corresponded with ceroptene, a compound
whose structure had been determined some years earlier by Nilsson (1959).
Other compounds were tentatively identifi ed as kaempferol methyl ethers by comparison
of spot color with colors generated with known fl avonols, but structural
work was not taken further. Four pigment patterns emerged, referred to as I, II,
III, and IV by those workers. Plants from the Hoffman Hill site were either yellow
or green backed. The yellow-backed plants exhibited pigment pattern I and
chromosome counts revealed them to be tetraploids. The two green-backed plants
were triploids with pigment pattern IV. The Painted Cave population consisted of
yellow-backed and green-backed plants. The yellow-backed plants exhibited two
chromatographic patterns, I and II. All plants of both colors were shown to be
tetraploids. The three green-backed plants examined exhibited chromatographic
pattern IV; two were triploid, and one was tetraploid. The collections at Refugio
Pass yielded green-, yellow-, and white-backed individual plants. Five yellowbacked
plants had chromatographic pattern I; three of the plants were diploid,
one was a tetraploid, and the fi fth was a triploid. Yellow-backed plants from this
population with chromatographic pattern II were either diploid or triploid. Whitebacked
plants with pattern III were tetraploids, and so on. In a summary statement,
the authors pointed out that 10 of the 12 possible combinations of ploidy
level and chromatographic pattern have been observed. It was clear that pigment
type and ploidy level were not correlated, with the possible exception that all
white-backed plants in the Refugio Pass sample were tetraploids. The complexity
of the data precluded any defi nitive statement as to whether the observed combinations
originated via auto- or alloploidy.
Additional information on chemical variation within this species came from studies
of exudate and internal (vacuolar) pigments based on broader collections of the
fern (Star et al., 1975a, b). Exudate fl avonoids, identifi ed from specimens representing
the range of the species, were identifi ed as ceroptene [221], the C-methylfl avonol
pityrogrammin [222], and two derivatives of kaempferol, the 4′-methyl ether [223]
and the 7,4′-dimethyl ether [224] (see Fig. 2.69 for structures 221–224).