Hyalis argentea var. argentea

Hyalis argentea var. argentea is a plant that spends most of a growing season being mistaken for something else. The leaves are narrow, silver, and whorled along willowy upright stems, so the whole clump reads as an ornamental grass from any distance at all, and the effect is entirely convincing until the flowers open. Then the family shows: this is an aster relative, in the Asteraceae, and the flowers on the taller stems carry only a few ray florets each but are attractive in a spare, high-desert way that suits the foliage exactly. A sub-shrub or perennial to about three feet, clump-forming and modestly stoloniferous.

This plant is a Woodlanders introduction from Mendoza Province, Argentina, and has been hardy and evergreen here in Aiken, South Carolina. That combination is the whole reason the plant is worth your attention. Mendoza sits in the rain shadow of the Andes, high, bright, and dry, and the silver of the foliage is the plant's answer to that light. What was not obvious in advance is that the same construction would carry a South Carolina winter without losing the leaves, which is a genuinely useful trait in a silver plant; most of the silver perennials Southern gardeners try either rot in humidity or go bare and ugly in January.

The names describe what you see. Hyalis comes from the Greek for glassy or transparent, apparently for the papery, translucent quality of the flower bracts, and argentea is simply silvery. The genus is small and South American, and this is very nearly the only member anyone in North American horticulture has grown. Older references file the family as Compositae; Asteraceae is the current name for the same group, and both turn up on labels.

Use the plant as a silver accent in a sunny, sharply drained site, and place with the same logic you would use for a small grass: in a drift, at the front of a border, along a gravel path, or spilling toward a walk where the low winter light can catch the foliage. Pair with agaves, Dasylirion, rosemary, muhly grass, and the drier salvias. Water through establishment and then very little; the enemy is wet feet rather than cold. Divide or transplant in early spring if the clump spreads further than wanted. Very few American nurseries carry this plant, and the ones that do got the plant from here.