A methanol: water extract of tomato (Lycopersion esculentum Mill.) apices increased the growth of the alga Chlamydomonas reinhardtii. The active substance from the dried shoot apices was purified by C18 flash column and high performance liquid chromatography. The purified extract enhanced the growth of tomato, corn (Zea mays L.), and rice (Oryza sativa L.) seedlings at concentrations less than 1.0 mg·liter-1. With Chlamydomonas, the purified extract increased cell division 111% at 0.1 mg·liter-1 and chlorophyll content 23% at 10 mg·liter-1 in 18 hours. Nuclear magnetic resonance and mass spectroscopy indicated that the purified fraction was a mixture of compounds having sugar moieties. Analysis by thin layer chromatography showed that the fraction was ninhydrin positive and more polar than the known plant hormones studied.