Juncus effusus 'Unicorn'

The following was received via email:

We have grown from seed the Juncus effusus and in amongst them were larger plants that appear to be or of similar characteristic as the 'Unicorn' . Can Unicorn be grown from seed or is it best propagated by divisions? If it can be produced from seed do you know of a source where we could purchase some? Thank you for any and all information your are able to provide us.

Marcy
Perennial Grower