Chocolate lowland climate in the narrow band of latitudes where cacao is grown (20 degrees north and south of the equator), the commercial company Mars, Incorporated and the University of California, Berkeley are conducting genomic research in 2017–18 to improve the survivability of cacao plants in hot climates. Chocolate is made from cocoa beans, the dried and fermented seeds of the cacao tree ("Theobroma cacao"), a small, 4–8 m tall (15–26 ft tall) evergreen tree native to the deep tropical region of the Americas. Recent genetic studies suggest the most common genotype of the plant originated in the Amazon basin and
Tree and frost, and the seed germinates in the spring. Pine cones may similarly be hoarded by red squirrels, and grizzly bears may help to disperse the seed by raiding squirrel caches. The single extant species of Ginkgophyta ("Ginkgo biloba") has fleshy seeds produced at the ends of short branches on female trees, and "Gnetum", a tropical and subtropical group of gymnosperms produce seeds at the tip of a shoot axis. The earliest trees were tree ferns, horsetails and lycophytes, which grew in forests in the Carboniferous period. The first tree may have been "Wattieza", fossils of which have been found