A small sample of the great diversity of seed sizes and shapes.

Like fish, plants vary widely in the number of offspring they produce, ranging from those that produce many small seeds to those that produce a few large seeds (fig. 9.6). The sizes of seeds produced by plants range over 10 orders of magnitude, from the tiny seeds of orchids that weigh 0.000002 g to the giant double coconut palm with seeds that weigh up to 27,000 g. While some orchids are known to produce billions of seeds, coconut palms produce small numbers of huge seeds. At this scale it is clear that there is a trade-off between seed size and seed number and while there are complexities that must be accounted for (Harper, Lovell, and Moore 1970), botanists long ago described a negative relationship between seed size and seed number (Stevens 1932).