Taking a page out of a famous musician’s book, Celtica gigantea is “the Grass Formerly Known as Stipa gigantea”. The scientific name for golden oats changed with the publication of this paper: Vázquez, FM and M Barkworth. 2004. Resurrection and emendation of Macrochloa (Gramineae: Stipeae). Botanical Journal of the Linnean Society. 144:483–495. The name change has yet to cascade through many of the online garden publications and databases, so an Internet search is more successful if you use the synonym, Stipa gigantea. The genus Celtica is monotypic, so this taxon is the only species within the newly-formed genus.
For an illustration of the plant (instead of only the seeds as in this photograph), see Celtica gigantea in the Icones plantarum rariorum from Missouri Botanical Garden’s Rare Books Collection. Native to southwestern Europe and northwest Africa, Celtica gigantea is yet another RHS Award of Garden Merit plant. The RHS also has gardening information for golden oats.
Photography resource link: The photography of Edward Weston, an early 20th century master photographer (I’ve just picked up a book with a collection of his photographs). In particular, see his Natural Studies, Point Lobos & Death Valley and Clouds, Trees & Water series.