Plant sources of fiber
Legumes such as soybeans contain dietary fibers.Some plants contain significant amounts of soluble and insoluble fiber. For example plums (or prunes) have a thick skin covering a juicy pulp. The plum's skin is an example of an insoluble fiber source, whereas soluble fiber sources are inside the pulp.

Soluble fiber is found in varying quantities in all plant foods, including:

legumes (peas, soybeans, and other beans)
oats, rye, chia, and barley
some fruits and fruit juices (including prune juice, plums, berries, bananas, and the insides of apples and pears)
certain vegetables such as broccoli, carrots, and Jerusalem artichokes
root tubers and root vegetables such as sweet potatoes and onions (skins of these are sources of insoluble fiber)
psyllium seed husk (a mucilage soluble fiber).
Sources of insoluble fiber include:

whole grain foods
wheat and corn bran
nuts and seeds
potato skins
flax seed
lignans
vegetables such as green beans, cauliflower, zucchini (courgette), celery, and nopal
some fruits including avocado, and bananas
the skins of some fruits, including tomatoes
The five most fiber-rich plant foods, according to the Micronutrient Center of the Linus Pauling Institute, are legumes (15–19 grams of fiber per US cup serving, including several types of beans, lentils, and peas), bran (17 grams per cup), prunes (12 grams), Asian pear (10 grams each, 3.6% by weight), and quinoa (9 grams).

Rubus fruits such as raspberry (8 grams of fiber per serving) and blackberry (7.4 grams of fiber per serving) are exceptional sources of fiber.