TOW (& Answer)...

The question was what are the symptoms of Hydrangea poisoning?  It is interesting to note that the hydrangea is considered to be one of the most poisonous plants (something I did not know).  All parts of the plant are toxic (especially the flower buds).  The symptoms begin several hours after ingestion.  The poison of the plant decomposes in the intestines and is released.  This causes gastroenteritis and other cyanide poisoning symptoms.  Cyanosis may develop, and in cases of large doses, convulsions, coma and death.

The question (& answer) were taken from p. 183 of The Poisons and Antidotes Sourcebook by Turkington.  The book was published by Facts on File in 1999.