GUANGZHOU -- Three people died and another 12 were hospitalized in South China after ingesting a poisonous herb known as "heartbreak grass" on Wednesday.

The 15, all workers in a eucalyptus plantation in Lashi village of Zijin county, Guangdong province, drank self-made medicinal liquor mistakenly made with Gelsemium elegans, initial investigation has showed.

The local government said the workers all showed symptoms of poisoning after having supper on Wednesday night, with one dying immediately and another two on the way to hospital.

Further investigation is under way.

Gelsemium elegans contains gelsemine, which when ingested can cause dizziness, convulsion and, in some cases, death.