Chia seeds (Salvia hispanica) under a stereo microscope. Chia is native to central and southern Mexico and Guatemala. Whole seeds are used for nutritious drinks and as a food source, and ground as flour in both countries. The plant was grown by the Aztecs in pre-Columbian times. Today, Chia is grown commercially in many countries worldwide, although it is still probably best known in the United States as the sprouts which are grown on "Chia Pets." The characteristic seed coat patterns are lost under a scanning electron microscope; this image was obtained using a low-magnification dissecting microscope after several drops of water were added to the seeds. A polysaccharide in the seed coats started to swell immediately and formed a viscous liquid. For this quality, the seeds are sometimes added to drinks.