The spread along the coast of Southeast Asia and around China may have taken place about the beginning of the Christian era, but it is also possible that sorghum arrived much earlier in China via the silk trade routes. The case is similar for Australia. There are other classes of sorghums such as sorghos, grass sorghums, broom-corn sorghum and specialpurpose sorghum. The sorghum kernel varies in colour from white through shades of red and brown to pale yellow to deep purple-brown. The most common colours are white, bronze and brown.
Kernels are generally spherical but vary in size and shape.
The grain is partially covered with glumes. Large grains with corneous endosperm are usually preferred for human consumption. Yellow endosperm with carotene and xanthophyll increases the nutritive value. Sorghum grain that has a testa contains tannin in varying proportions depending on the variety. Pearl millet may be considered as a single species but it includes a number of cultivated races.