Jim, You bring up a very interesting point -- the chemicals (alkaloids?) presented in plants are valid criteria for classifying them. For example, look at Allium. And for that matter, Brassica and the Brassicaceae in general. There are others -- I vaguely remember a case of two species that were indistinguishable except that they attracted non-overlapping pollinators. And isn't Rhus separated from Toxicodendron by the presence or absence of urushiol? As I bake my own, whole wheat, and as I whip up my own, Mayo (though cream cheese sounds intriguing), and I usually add tomato. Oh, any cress. David E. S.F. Peninsula, where it finally stopped raining.