AUSTIN, Texas (AP) — A chewable African plant that investigators in Texas believe may be linked to terrorism groups has quietly launched a lengthy investigation in Houston and produced multiple arrests.

The Austin American-Statesman reported Sunday (http://bit.ly/18SfJ9U) that Muslim civil rights groups are now questioning whether the Texas Department of Public Safety has crossed a line. The agency last year included the olive-shaped leaves known as khat on a statewide threat assessment.

Khat is grown in the Horn of Africa. State investigators say plant sales are suspected to benefit terrorist groups, but there is wide disagreement over the strength of that link.

A state trooper noticed two men chewing khat while making a routine traffic stop near Houston last year. DPS spokesman Tom Vinger says an investigation hasn't yet led to terrorism-related charges.

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Information from: Austin American-Statesman, http://www.statesman.com

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