ABSTRACT

Cycads are ancient seed plants (living fossils) with origins in the Paleozoic. Cycads are sometimes considered a “missing link” as they exhibit characteristics intermediate between vascular non-seed plants and the more derived seed plants. Cycads have also been implicated as the source of “Guam’s dementia”, possibly due to the production of S(+)-beta-methyl-alpha, beta-diaminopropionic acid (BMAA), which is an agonist of animal glutamate receptors (GLRs).