Closely related to Arenaria, this low-growing woody perennial has small needle-like leaves and white flowers in summer. Grow in rock crevices with regular water and protection from afternoon sun. Native to rocky areas in European mountains.   Caryophyllaceae

This low-growing perennial forms a carpet small needle-like leaves and white flowers in summer. Grow in part shade in gritty, moist soil. Native to scree in mountains of Asia and North America.   Caryophyllaceae