Scientific: Nassella tenuissima (formerly Stipa tenuissima)
Common: Silky thread grass, Mexican feather grass, Mexican needle grass, pony tails
Family: Poaceae
Origin: Dispersed widely on rocky slopes, dry open woods and dry prairies from New Mexico and Texas south through central Mexico.

Pronounciation: Nas-SEL-la ten-u-is-SI-ma

Hardiness zones
USDA 7-11

Landscape Use: Best planted in groups as an accent for small landscaped spaces where it can colonize, but not escape cultivation. Rock garden, transitional landscapes. Best used when viewed from a distance.

Form & Character: Very light and bright, breezy, airy, soft and wispy. This grass plant suggests the movement of air and has a cooling, softening effect in the landscape.

Growth Habit: Perennial herbaceous bunch grass clumping to 3 to 4 feet in height with equal spread.

Foliage/Texture: The leaves are bright green and are exceptionally narrow, but are 6 to 14 inches in length. They are rolled inward very tightly so that they appear as thin wiry filaments; very fine texture.

Flowers & Fruits: The inflorescence is a silvery soft nodding panicle 6 to 12 inches long; fruits are inconspicuous.

Seasonal Color: Mexican feather grass blooms in winter through spring with a greenish flower cluster which persists well into the summer as it ripens to golden brown.

Temperature: Tolerant

Light: Filtered sun to partial shade best in lower Arizona desert climates; otherwise, full sun.

Soil: Well drained

Watering: Weekly to bi-weekly deep irrigations in summer will keep plants robust.

Pruning: As with other bunch grasses, occassionally shear (mid to late summer to remove seed heads) or burn to the ground (once per year) to remove thatch (dead and slow to decompose leaves because of the dry climate) and re-induce vigor.

Propagation: Division anytime, easy by seed.

Disease and pests: None in south central Arizona.

Additional comments: In general, silky thread grass is an incredibly visually stunning bunch grass for that elegant and wispy look......but BEWARE landscape architects and gardeners, this little devil is reportedly vigorously invasive, especially in southern California. I suspect (though have no data) that this beautiful grass has the potential to be invasive in the grassland landscapes of Prescott, Payson, and Miami and Globe, Arizona. I recommend that it is best if one plants this fecund bunch grass where you won't mind its invasive tendency. The cultivar 'Pony Tails' is a selection noted for its abundant and very showy panicles.

Nassella tenuissima likely will go dormant during hot dry months of summer in Phoenix unless planted in a shaded location. There are 13 recognized species of Nassella that are native all over North America.

Some wonder which is more smooth? Silky thread grass? Or the Edge's guitar solo at the 4:30 mark of Mysterious Ways performed by U2 at Slane Castle in Ireland? I've seen both up close and there's no question in my mind...All Hail to The EDGE!