A thank you to Michael Mazars of France (aka Mikl - Concept-Photo.fr (CRBR)@Flickr) for contributing today's photograph of Linum grandiflorum 'Rubrum' via the Botany Photo of the Day Flickr Pool. Much appreciated!
Linum grandiflorum is native to northern Africa, specifically Algeria. English common names it is known by include crimson flax, scarlet flax, red flax and flowering flax. Cultivated in gardens as an annual ornamental, it occasionally escapes and naturalizes (in such places as Britain, southern Europe, California, and elsewhere in northern Africa).
If researching this taxon, you may find references to it being called Linum grandiflorum var. rubrum. This name only seems to have been used in horticulture (if you click on the link, you'll see "hort." after the var. rubrum part, meaning "hortulanorum" or "of gardeners"), i.e., it was never validly scientifically described and published. In order to bring the name in compliance with the rules surrounding the naming of botanical and cultivated taxa, it was shifted to Linum grandiflorum 'Rubrum'.