There are a number of plants which produce nectars with toxic components.  A
good review of this topic can be found in Barker, Poisoning by Plants in
"Honey Bee Pests, Predators, and Diseases", 2nd edition, edited by R. Morse
and R. Nowogrodzki.  Some of the better know examples include the
Rhododendrons (esp  R. ponticum and R. luteum), Gelsemium sempervirens
(yellow jessamine), and Kalmia latifolia (mountain laurel).  We analyzed a
honey produced in southwest Virginia a couple years ago and found levels of
grayanotoxins I and III higher enough to make a person extremely ill (which
it had done).  The presumed source was thought to be Kalmia.
 
>To:            PCCSSW.MAILER SSW[PCCSSW.MAILER]
>From:          Mihaly [log in to unmask]@FDAORAPAR
>Subject:
>Date:          Wednesday, April 26, 1995 at 11:31:09 am EDT
>Attach:
>Certify:       N
>
>---------------------------- [Message Follows]
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>
>Does anyone know if there are any flowers or other nectar sources that
>produce a toxic honey and if so what are the toxins. Also an off the wall
>question : Can a queen bee sting while laying an egg or are the functions
>mutually exclusive? Thankx  Mihaly ([log in to unmask])
>
Richard Fell     e-mail: [log in to unmask]
Department of Entomology, Virginia Tech
Blacksburg, VA 24061
703-231-7207  Fax 703-231-9131