Vegetation includes all plant life and is the source of all plant foods. Tropical vegetation shows characteristics that distinguish it from that of the temperate zone. Tropical growth is luxuriant; the fruit is abundant and usually fragrant and luscious; the crops are many a year; all ages grow together and ripen successively. The inclusion of tropical products in the diet of colder climates is not simply bringing foods at seasons that they would not grow in any but a tropical region, but is bringing foods of ever new growth almost continuously. The tropics also supply some foods that other regions cannot; for example, many spices.

Needs of vegetation itself are those common to life, for vegetation is living. It is also working. For living it needs itself water, air, and food suited to its uses. Plants make in themselves from their own foods, that would not nourish animals and humankind, substances that serve as human foods and for animals too. This is only part, though a most significant part, of the work that vegetation does through its life-activity.

Supplies of food from vegetation are most varied, as they include grains, vegetables, fruits, spices, nuts, leaves and seeds serving as beverages, and seeds producing oil. These include all food-constituents needed for the life of humankind, though an exclusively vegetable diet is not advised generally by food-scientists. It is, however, upon vegetation alone that reliance must be placed for starch, and mainly for sugar too. Protein and mineral matter it furnishes in common with animal life, and is beginning to rival animal life as a source for fats, since the consumption of vegetable oils is greatly increasing.

Humanity not only uses vegetation for food and other living-needs but also learns much from it concerning nature's workings. Through this it ever finds new aid possible.