Specimens of the genus Wolffia , an aquatic plant, are less than 1 millimeter long and 0.3 mm wide. Related to duckweed (genus Lemna), they are rootless and form mats in ponds and calm streams.
These aquatic plants produce a tiny flower that becomes the smallest fruit , which occupies almost the entire body of the mother plant.
This fruit measures just 0.25 mm and has a mass of about 70 micrograms , that is, it is only a little more mass than a simple grain of sand has.
They are aquatic plants and resemble cornmeal flakes floating in water. They are free-floating, green or yellow-green in color, and without roots.
Epiphytic orchids , non-parasitic plants that grow on top of others, produce seeds the size of a speck of dust, with about 992 million seeds per gram.
As they do not contain nutritive tissue, the seeds must be stored in a certain type of fungus in order to germinate. This may mean that they have to fly hundreds of kilometers, but they are so light that they are easily dispersed in the wind.