[Pawpaw, Mamao, Lechoza, Carica papaya]
The only notable member of the family Caricaceae, the Papaya is of Central American origin, but now grown in tropical regions throughout the world. It is very distantly related to Cabbages, but is this plant a "branchless tree" or a giant herb? Technically it's an herb.
Unripe papayas are used in Thailand, Laos and Vietnam for their famous green papaya salads, and as a cooked vegetable in India and the Philippines. Ripe papayas are eaten as fruit and made into various fruit drinks and concoctions. They are used worldwide as meat tenderizer and digestive aid. In the photo are a medium size Mexican papaya (upper left, 10-1/2 x 5-3/4 inches 5-1/2 pounds), a typical Hawaiian papaya (lower right, 5-1/2 x 3-1/4 inches 1 pound) and an unripe "green" papaya cut in half (top right).
More on the Brassicales Family.
Hawaiian papayas have flesh that is sweeter, more delicately flavored, and lighter in color than Mexican papayas. On the other hand, the photo specimens were purchased for 2014 US $2.99 / pound for the Hawaiian, $0.69 / pound for the Mexican, and $1.49 / pound for the green.
Ripe papaya seeds have a spicy taste similar to a mild black pepper, and are sometimes used as a substitute for that spice, or in India as an adulterant. Young papaya leaves are eaten like spinach in some tropical areas, but mature leaves have an effect on the heart similar to digitalis, though they can be cooked in several changes of water to remove this effect and their bitterness.
Unripe papayas can be found in markets serving a South or Southeast Asian community, particularly Filipino. Ideally, they should be completely white as in the photo above, though I've successfully used papayas with just a trace of pink blush around mostly black seeds.