The "kelp"

Senecio vitalis  

As though swaying in ocean eddies, this yellow-green Senecio has semi-prostrate stems and narrow, upward-reaching leaves. Its shrubby (to 2 feet tall) nature makes it an excellent backdrop for a dry garden. In front are Kalanchoe luciae ‘Fantastic’ and spiky Crassula capitella thyrsiflora ‘Campfire’, a chameleon that’s green in part sun, vermilion in full.