seeds

This entry concerns true seeds, not the spores produced by plants like ferns, mushrooms and mosses.

coco de mer nut

©iStockphoto.com/narvikk

The biggest seed

The largest seed is that of the coco de mer (Ludoicea maldivica Pers. ex H. Wendl), which is also the plant with the largest leaves. The heaviest reported seed weighed 16.66 kilograms (36.73 pounds).

Despite its common name, the tree is a fan-palm, not a true coconut. They are slow growing; males reach a height of 30 meters and the females 24 m (the sexes are separate). They live 200 to 400 years. Female trees reach bearing age in 20 to 40 years (a trunk doesn't even appear for 15 years!). Individual fruits require 6 to 7 years to mature.

The fruit was known for centuries from specimens washed up on beaches or adrift at sea, before the plant itself was discovered. These floating seeds, however, were rotten, for viable fruits sink. Finally two groves were discovered in the Seychelles, the only places where the plant grows naturally. Since 1978 collection and sale of coco-de-mer nuts has been a government monopoly, to protect the groves.

Many descriptions of the size of the coco de mer confuse the seed with the fruit. The fruit contains from 1 to 3 seeds. In June 1999, the Seychelles Bureau of Standards weighed a fresh fruit, considered the world record holder, at 36.42 kilograms.

Newsletter of the Seychelles Islands Foundation.

The smallest seed

The smallest seeds are those of certain tropical orchids that grow on the trunks of trees (epiphytes). Their seeds are barely visible to the naked eye.

Seed longevity

The oldest seed successfully germinated is a date palm seed (Phoenix dactylifera L.), one of five recovered in the 1960's at an excavation near Masada, Israel. In 2005, the seeds were given to botanists who attempted to germinate them. Radiocarbon dating of parts of the seeds gave a range of 206 bce to 392 ce, so the seed was about 2000 years old.¹ The sapling has been named “Methuselah.”

The record was previously held by the species Nelumbo nucifera, the Sacred Lotus.² At the time of germination, the seed was roughly 1300 years old, as determined by carbon-14 dating.

Tales of germination of wheat found in ancient Egyptian tombs persist but are unfounded. The Egyptians have been guiding tourists for more than 2000 years, so they have had plenty of time to find ways of capturing their interest.

Controlled experiments on seed longevity are rare. In 1879, an American professor, William James Beal, buried 20 open, upside-down bottles containing sand and an assortment of seeds of common plants. A bottle has been dug up every 20 years thereafter. By 2000, only the seeds of the moth mullein and cheeses plant could be germinated.

1. Sarah Sallon, Elaine Solowey, Yuval Cohen, Raia Korchinsky, Markus Egli, Ivan Woodhatch, Orit Simchoni and Mordechai Kislev.
Germination, genetics and growth of an ancient date seed.
Science, vol. 131 no. 1464 (13 June 2008).
doi:10.1126/science.1153600

2. Jane Shen-Miller et al.
Exceptional seed longevity and robust growth: Ancient Sacred Lotus from China.
American Journal of Botany, volume 82, pages 1367-1380 (November 1995).