They occur in algae, fungi, lichens, bryophytes and seedless vascular plants.

The name of the group is very similar to the cannabis plants "Sinsemilla," which are the unfertilised, thus seedless, female plants.

Spores and pteridophytes are conserved in seed banks, but other seedless plants, such as tubercrops cannot be preserved this way.

This technique is used to preserve seedless plants and plants which reproduce asexually.

Fern allies are a diverse group of seedless vascular plants that are not true ferns.

They have some structural and developmental similarities to the sieve elements of seedless vascular plants.

The horsetails and their fossil relatives have long been recognized as distinct from other seedless vascular plants.

Some seedless plants can also be considered annuals even though they do not flower.

The term pteridophyte also refers to ferns and a few other seedless vascular plants (see classification section below).