Telium

Telium, plural telia, are structures produced by rust fungi as part of the reproductive cycle.

[1] They are typically yellow or orange drying to brown or black and are exclusively a mechanism for the release of teliospores which are released by wind or water to infect the alternate host in the rust life-cycle.

The telial stage provides an overwintering strategy in the life cycle of a parasitic heteroecious fungus by producing teliospores; this occurs on cedar trees.

A primary aecial stage is spent parasitizing a separate host plant which is a precursor in the life cycle of heteroecious fungi.

The life cycle of rust fungi can have up to five different spore stages and can get quite complex.