The world's largest seed comes from the Coco de Mer (Lodoicea maldivica). Other common names used are Seychelles Island Palm, coco fesse, Maldive coconut, love nut, Seychelles nut, sea coconut, and double coconut. It originates from the islands of Praslin and Curieuse in the Seychelles Islands. It formerly also was found on the small islets of St Pierre, Chauve-Souris, and Ile Ronde (Round Island), all located near Praslin, but had become extinct there for a time until recently reintroduced.
Coco de Mer Tree
The tree grows to 25 to 34 m tall. The leaves are fan-shaped, 7 to 10 m long and 4.5 m wide with a 4 m petiole. It is dioecious, with separate male and female plants.
These plants grow wild on nutrient-starved, rocky soil. Nitrogen and phosphorus are two natural fertilizers — nutrients — that these (and other plants) need. There isn’t much of either on the islands where these palms grow, so the plants are frugal. They sprout fronds using only about one-third the nutrients needed by leaves of 56 neighboring species of trees and shrubs. What’s more, coco-de-mer palms scavenge a lot of the nutrients shed in their own dying leaves. These trees can reuse 90 percent of that prized phosphorus from the fronds it’s about to drop.
A single seed may be 12 inches long, nearly three feet in circumference and weigh 20 kg (over 40 pounds, or about as much as a 4-year-old boy). The seed may take 6 to 7 years to mature and a further two years to germinate. However, that won't happen until the palm first reaches plant “puberty.” On the nutrient-poor ground, this reproductive coming-of-age may take 80 to 100 years. Only then can one of these palms yield its first seed. Throughout a female coco-de-mer palm’s life of several hundred years, it may bear only about 100 seeds.
The Coco de Mer is a drupe.
The Difference Between a Nut and a Drupe
Most of what we think of as nuts aren't really nuts at all, they are actually drupes.
A true nut, botanically speaking, is a hard-shelled pod that contains both the fruit and seed of the plant, where the fruit does not open to release the seed to the world. Some examples of botanical nuts are chestnuts, hazelnuts, and acorns.
A drupe is a type of fruit in which an outer fleshy part surrounds a shell (what we sometimes call a pit) with a seed inside. Some examples of drupes are peaches, plums, and cherries—but walnuts, almonds, and pecans are also drupes. They're just drupes in which we eat the seed inside the pit instead of the fruit.
The Largest Seed Embryo
Because it has the largest seed embryo, a tropical tree (Mora oleifera) found in South American tidal marshlands and estuaries is another possibility for the world's largest seed. Palomar College says that "seeds of M. oleifera may be up to 7 inches (18 cm) long and up to 5 inches (8 cm) wide."