Ricin Poisoning from Phloem?

[William E. Williams]

Dear Plant-Eders,

We're about to introduce a phloem assay using Ricinus into our 
introductory biology sequence, and of course the question of toxicity 
has come up. The web references I've found are somewhat 
contradictory, saying on the one hand that ricin is synthesized only 
in the endosperm and thus only present in the seeds, but on the other 
that aphids forced to feed on the leaves die rapidly, presumably 
because of ricin poisoning. Of course we'll advise the students to 
wear gloves and keep hands away from their mouths and avoid 
contaminating areas of skin with open sores, etc., but does anybody 
have a definitive reference on how poisonous parts of the plants 
other than the seeds are?

We're also having trouble getting much phloem sap. Any suggestions 
about where to cut, optimal plant size, growth conditions, etc.?

-W2
-- 
William E. Williams <MailTo:WEWilliams at smcm.edu>
Biology Department
Saint Mary's College of Maryland
18952 E Fisher Road
Saint Marys City, MD 20686-3001
USA
Voice: (240)895-4365
FAX:   (240)895-4996

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