Xanthocephalum gymnospermoides var. eradiatum

A principally Mexican species entering the United States peripherally in southeastern Arizona and western Texas. As the name suggests, var. eradiatum differs from the typical variety in lacking ray flowers.

Flowering stems at the Cascada de Basaseachic overlook, Sierra Madre Occidental, Chihuahua, Mexico, 8 Sep 2009. Photographed on a trip with the American Penstemon Society.

Pseudanthia at the Cascada de Basaseachic overlook, Sierra Madre Occidental, 8 Sep 2009.

Side view of pseudanthia, showing phyllaries, at the Cascada de Basaseachic overlook, Sierra Madre Occidental, 8 Sep 2009.

A halved pseudanthium at the Cascada de Basaseachic overlook, Sierra Madre Occidental, 8 Sep 2009.

A cauline leaf at the Cascada de Basaseachic overlook, Sierra Madre Occidental, 8 Sep 2009.