The earliest vascular plants were seedless, reproducing with instead of seeds.
-cones
f-lowers
-spores
-pollen

Spores are highly resistant structures formed in response to adverse conditions and once formed they have no metabolic activity and can remain dormant for years.
Two kinds of organisms form spores, namely bacteria and fungi.
Bacteria form spores  basically for survival. Fungi  on the other hand form spores for reproduction and these are either sexual or asexual in nature.
Examples of fungal sexual spores are zygospores, ascospores and basidiospores. Examples of fungal  asexual spores (collectively known as conidia) are arthrospores, chlamydospores and blastospores.

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