All palms are flowering plants (angiosperms) and thus yield some type of fruit that is either fleshy or dry when ripe. According to Robert Lee Riffle and Paul Craft, authors of "An Encyclopedia of Cultivated Palms," there are nearly 2,300 species of palms. While not all grow with tree-like trunks, all produce branching clusters of tiny flowers that must be pollinated before developing into fruits.
The fruits of palms are botanically known as berries or drupes. According to the University of Hawaii and the Chinese Academy of Sciences, most palm fruits are berries since they most often produce one or more seeds embedded in a fleshy body. However, some palm species produce a drupe that has a large stone-like pit, or seed. The exocarp of the fruit is the outermost skin, the mesocarp often is fleshy or fibrous and the endocarp is the thin layer that surrounds the seed in the core. "An Encyclopedia of Cultivated Palms" notes that some palm species' fruits can contain as many as 10 seeds each. The fruits, like the palm's flowers, form in clusters.
There is much variability in the physical features of palm fruits across all the different palm genera and species. Fruits' outer surfaces can be smooth, soft and waxy or wood-like. The fruit of the date, Phoenix dactylifera, is smooth and soft when ripe. A dried coconut Cocos nucifera, is hard and woody under its buoyant outer husk. Spines and scales also can cover a palm fruit. Colors of the fruits vary just as dramatically. They can be red, black, white, orange or purplish, again determined by each species' genes.
In all palms, each seed contains only one plant embryo. Once the seed is mature, released from the mother palm plant and in contact with optimal growing conditions, the embryo inside the seed germinates. All palms are monocotyledons, or monocots, and thus emerge as seedlings with only one seed leaf.
The size of fruits is widely varied. Small, pea-like fruits are produced as well as massive, ball-like seeds. In fact, Riffle and Craft mention that the world's largest seed comes from species Lodoicea maldivica, native to the Seychelles.
Palm fruits develop immediately after the flowering season. Typically, palms flower during "warm months," which could mean late spring to summer in temperate regions or the monsoonal "wet season" in the tropics. Ripening ovaries become the fruits and need ample moisture and warmth to mature before temperatures cool or seasonal drought ensues. Fruits are retained on the branching flowering structure (called an infructescence) until they mature and become too heavy for the plant tissues to hold them. They then naturally drop to the soil or water below.