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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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Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

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Thursday - August 16, 2012

From: Brownsville, TX
Region: Southwest
Topic: Non-Natives, Problem Plants, Shrubs
Title: Male or female Jatropha curcas from Brownsville TX
Answered by: Barbara Medford

QUESTION:

How do know the sex of a young Jatropha C. plant? how many weeks before you can tell a boy/girl plant ?

ANSWER:

Somewhat to our surprise there were several species of the genus Jatropha, a member of the Euphorbiaceae (spurge) family, native to North America. One that comes closest to your identification of Jatropha C. is Jatropha cathartica (Berlandier's nettlespurge). According to our Native Plant Database, it is endemic to Texas in North America, but also grows in Mexico. This USDA Plant Profile Map shows that it does grow in several counties in South Texas, including Cameron.

Our first question (never actually having heard of this plant before) was "What is Jatropha?" From the African Development Bank - Renewable Energy we found an article with that very title: What is Jatropha? It appears that the plant you are most likely asking about is Jatropha curcas, which is native to Central and South America, but has spread all over the world in tropical and sub-tropical climates. This USDA Plant Profile Map shows this plant has been introduced into Hawaii, Puerto Rico and Florida.

Since this is a non-native and out of our realm of plants native to North America, we are going to give you links to some websites to help you answer your own question. We are curious as to why you would want to propagate this plant? It can be invasive, it has serious toxicity, and isn't particularly attractive. Perhaps you're planning home production of biodiesel for the family car?

From General Biodiesel Jatropha curcas: Poison shrub or environmental savior?

Jatropha curcas

Wikipedia Jatropha curcas

Tropilab Inc. Jatropha Curcas - Physic Nut

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