But finding seeds or cuttings of true species has never been easy.

When there are no living stumps, seeds of naturally-occurring species are used.

There are the seeds of invasive species that take advantage of the storm's disturbance to insinuate themselves into new soil.

They are also vectors for the seeds of introduced species of plants, including several types of noxious weed.

Once these were established, birds began to return, bringing seeds of other species with them.

Mourning Doves show a preference for the seeds of certain species of plant over others.

The seeds of Japanese maple and similar species require stratification in order to germinate.

It occurs mainly in the root and/or seeds of different species of cotton plants.

Recent efforts have focused on the direct seeding method where seed of native species is ploughed into a scraped trench.

On occasion, seed of rare and endangered species need immediate propagation, limiting our opportunities for studying physical characteristics.