Brian Kemble is curator at the Ruth Bancroft Garden in Walnut Creek. His monthly column focuses on drought tolerant plants and dry gardens.

Among the relatives of the agaves and the yuccas is a small genus called Hesperaloe, native mostly to northern Mexico although one kind makes it across the border into Southern Texas. The best known of these is Hesperaloe parviflora with pinkish-red flowers on long stalks blooming during the summer months.

It is much valued for its tolerance of both heat and cold as well as its ease of cultivation and long flowering season. In recent decades several new kinds of Hesperaloe have made their way into horticulture and one of these is Hesperaloe tenuifolia, native to the state of Sonora in Northwestern Mexico.

If Hesperaloe tenuifolia is only now finding its way into nurseries, this is not surprising because it was not even named scientifically until 1997.

The name tenuifolia means “slender leaves,” and indeed the plant’s tufts of long narrow leaves bring to mind large gray-green grass until one notices the fine curling threads peeling from the leaf edges.

Curling fibers along leaf margins are a trait found in numerous other plants in the Agave family, including some species of agaves as well as numerous yuccas. Although the leaves of Hesperaloe tenuifolia rise upward, and plants are more vertical than horizontal, the leaves on the outside of the clump arch gracefully outward so that plants do not appear stiff. While the clump is about 2 to 3 feet tall, the flower stalk rises much higher, often more than 6 feet.

Hesperaloe tenuifolia sends up its stalks and begins to bloom in spring, with flowering continuing through the summer months. While an agave’s flowers begin at the lower end of the flower stalk and progress upward in sequence, H. tenuifolia has numerous small clusters of flowers along the upper part of its stalk, and these produce new flowers one-by-one in no particular order.

At any given time, there will be flowers opening here and there all along the stalk. The flowers themselves are pink at the bud stage and shaped like little tulip buds. The flowers open at night, and when they do so the petals curl back to show off the white inside of the flower and the yellow pollen at the middle.

This schedule is dictated by the moths and bats that serve as their pollinators, and the whiteness of the open flower helps them to be more visible in the twilight and early morning hours when the pollinators are active. Happily, they remain open into the morning hours to be enjoyed by those of us who don’t see so well in the dark. Even later in the day, the pink of the buds provides an attractive splash of color in the garden.

Like its relative Hesperaloe parviflora, H. tenuifolia is a tough plant tolerant of temperature extremes and needing only occasional water. It can endure winter lows to below 20 degrees and is not fussy about soil type although good drainage is recommended.

Undoubtedly it will gain in popularity as it becomes better known by the gardening public.

Email questions on drought-resistant plants to info@ruthbancroftgarden.org. Learn more about the Ruth Bancroft Garden at www.ruthbancroftgarden.org.