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Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Wednesday - August 19, 2009

From: San Marcos, TX
Region: Southwest
Topic: Poisonous Plants
Title: Toxicity of Yucca leaves San Marcos, TX
Answered by: Amy Johnson

QUESTION:

Can you tell me if Yucca constricta leaves are poisonous? I ran into one at night and the next morning had a hive-like, VERY itchy rash.

ANSWER:

The roots, at least, of Yucca constricta (Buckley's yucca) do contain saponins, which, while toxic to humans, are usually poorly absorbed and therefore do not usually irritate unless you are sensitive or allergic to them.  Incidentally, beneficial uses of these same saponins have been found for humans as well, usually involving cooking them to remove any toxicity.  You mentioned the leaves, and it is possible that some of the sap containing saponins from the plant could have escaped upon contact and caused the intense irritation in your skin, especially if you are sensitive or allergic to it.  It's also possible that there was more than just the Yucca itself involved - other pollen or bacteria could have been on the leaf or even your skin to begin with, and the abrasion caused by contact may have allowed one of those to penetrate and therefore irritate the surrounding skin.  Hopefully your rash is healing now - such a rash sounds very yucca!


Yucca constricta

Yucca constricta

Yucca constricta

 

 

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