From the Guidebook:
Planted in 1901 by the R.
H. Hamlins, early citrus growers, the Glendora bougainvillea
is the largest growth of this exotic plant in the United
States. The parent stock was brought to California by
a whaling ship about 1870. The vines are one of the best
remaining illustrations of the image of California as
a paradise that was spread by early 20th-century promoters.