The Geography of Phytochemical Races

2.7 North and Central America 117
The authors suggested that extrapolation beyond the specifi c area studied was not
warranted. It would be of interest to see what DNA sequence data might have to say
about red oak throughout its range.
2.7.21 Cnidoscolus spinosus (Euphorbiaceae)
Cnidoscolus is a genus of about 75 New World species, some of which have useful
properties such as C. chayamansa McVaugh, eaten as a spinach-like vegetable
(chaya), and C. elastica Lundell, which is true to its name in yielding a latex rich
in rubber (Mabberley, 1997, p. 166). The species of interest to us in this chapter is
C. spinosus Lundell, native to the western coast of Mexico. Kolterman et al. (1984)
examined the fl avonoid chemistry of this and related species from Mexico and Central
America. Eight populations were sampled, three from the northwestern part of the
range (ca. 22°N, vicinity of Tuxpan, State of Nayarit), two from the southeastern
part of the range (ca. 17°N, vicinity of Acapulco, State of Guerrero), and three from
roughly midway between the other two (ca. 19°N, vicinity of Manzanillo, State of
Colima) (Fig. 2.73). The fl avonoid profi les consisted of 3-O-glycosides of kaempferol
and quercetin and, interestingly from the chemosystematic point of view, lacked
the C-glycosylfl avones reported from the other two taxa. Signifi cant differences were
observed among the three populations as summarized in Table 2.21. The populations
Fig. 2.73 Map of Cnidosculus sites