[APWG] Science or unfounded rumor?

[Wayne Tyson]

"An interesting phenomenon associated with  foreign plant communities is the virtually complete absence of native hummingbird-pollinated plants in the areas long dominated by tree tobacco.  Such common natives as purple sage Salvia leucophylla, and pitcher sage S. spathacea, California fuchsia Zauschneria californica, heartleaved penstemon Keckiella cordifolius, and other penstemons are virtually absent from large areas populated by tree tobacco in the south coastal valleys and canyons.  Evidently the ubiquitous tobacco, with its year round production of yellow flower tubes supplying nectar, weans away many of the local hummingbirds from the seasonal flowers of native species.  Perhaps other plant species "designed" to attract the hummingbird simply do not receive sufficient pollination to maintain a local population.  Where tree tobacco is still relatively scarce in side canyons, any or all of the normal wild hummingbird plant species usually can be found.  (No author listed, "Control of the Aliens, Unnatural Plant Communities in the Santa Monica Mountains"  FREMONTIA, A Journal of the Native Plant Society  July 1989 22-24).  http://nathistoc.bio.uci.edu/Plants%20of%20Upper%20Newport%20Bay%20%28Robert%20De%20Ruff%29/Solanaceae/Nicotiana%20glauca.htm"

APWG: The preceding statement is specific in its assertions. Is it based on evidence or rumor? Where can I find the evidence? In the absence of evidence, should I conclude that this statement is solely based upon the opinion of the unnamed author, or what? Is conjecture a satisfactory foundation for action? Are such unequivocal statements acceptable in journals which purport to adhere to scientific standards of publication? Should such "information" be propagated through the scientific literature if it lacks solid evidence? How does this affect the credibility of the issue of alien species in general? 

WT
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