Dan,
You made a good point, which I later raised with the artichokes introduced by
the Italian Lusardi family in San Diego and spread by livestock through many
canyons and river basins. However, I took botanists with me on the field
surveys and we sampled areas beyond the Indian camps to test for Opuntia and
the nightshade. They felt the soil conditions would have been quite favorable
for those varieties of plants, yet none were found except at the Indian
camps. This led me to conclude we had Opuntia gardens that continued at least
100 years after cultural abandonment. As to the nightshade, sure it could
have been brought to the rockshelters by birds but if so why not elsewhere
and in rockshelters with no cultural material?
Ron May
Legacy 106, Inc.