(1)"The active principle isolated from coffee (Coffea arabica) by chromatography and identified as 1,3,7-trimethyxanthnine [caffeine] showed complete germination inhibition of Amaranthus spinosus and seven other noxious weed species through amylase activity inhibition." ... "They also found related purine alkaloids and fatty acids whichmonstrated allelopathic activity." Allelopathic Chemicals: Their Potential Uses for Weed Control

(2) Allelopathy in Trees and Forests: A Selected Bibliography

(3)Just a blog. "Coffee grounds benefit different plants in different ways when added directly to the soil ... "MCC :: Gardening Association - Related Events Calendar

(4)Farmers' perspectives on the role of shade trees in coffee production systems: an assessment from the Nicoya Peninsula, Costa Rica. : HighBeam Business: Arrive Prepared [A reference to an obscure reference. Perhaps the concern is for the coffee, not the shade tree.]

(5) phytotoxic compound (caffeine) isolated from extracts of leaves and seeds of coffee completely inhibited seed germination of Amaranthus spinosusy [spiny amaranth, prickly amaranth or thorny amaranth] - International Turfgrass Society Research Journal Volume 8, 1997. EFFECTS ON ROOT AND SHOOT GROWTH OF POA ANNUA L. SEEDLINGS OF P

(1)The Hilo station was first
> to establish that a SPRAY of 1-2% chemical caffeine (NOT coffee, certainly
> not coffeegrounds merely cast on the soil) dousing the ENTIRE plant will
> over time lower the slug population by killing just the BABY slugs &
> snails AFTER THE TREATED PLANT IS EATEN. [pbs] Oriental Lilies - Allelopathy - Caffeine

(2)Elisabeth C. Miller Library: Gardening Answers Search Results

(1)OKLAHOMA JUNIOR ACADEMY OF SCIENCE

(2)Plant Defense Responses

(3)Hypothesis for Seedling Experiment

There are a lot of these sites mentioning alleopathy and caffeine but no useful information. Just posted a few to show how silly this sort of thing can get. �3a is hereby discontinued.