Nassella tenuissima (Mexican feather/hair grass)

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Nassella spp.

needlegrass

Poaceae

Temperate grasslands of South and North America

Deer Resistant Drought Tolerant

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 7–10

Overview

Nassella is a genus of tufted, cool-season perennial grasses in the family Poaceae, with most of its roughly 100 species native to the grasslands of South and North America. Plants form dense tussocks 0.3-1 m (12-39 in) tall, with narrow, inrolled leaf blades and airy, nodding flower panicles held above the foliage in late spring and summer. Each floret bears a sharp-pointed seed tipped with a long, bent, twisting awn 2-9 cm (0.8-3.5 in) long that drives the seed into soil and animal coats. Several species are grown as ornamentals for their thread-like foliage and feathery seed heads, including N. tenuissima and the Californian N. pulchra. Others are damaging invaders: N. trichotoma (serrated tussock) and N. neesiana (Chilean needle grass) are declared noxious weeds across south-eastern Australia and parts of other countries, where they displace pasture and native grassland. The genus tolerates heat, drought, and poor soil, and many species self-seed heavily, the trait behind both their garden use and their weediness.

Native Range

Nassella is native mainly to the Americas, concentrated in the temperate grasslands and steppe of South America, especially Argentina and Chile, with further species in western North America such as the Californian N. pulchra. Several species have naturalised and turned invasive well beyond their native range, notably in Australia, New Zealand, and South Africa.

Suggested Uses

Ornamental species are grown in gravel gardens, dry borders, and mass plantings for their thread-like foliage and feathery seed heads, spaced 30-45 cm (12-18 in) apart. Where a species is listed as a noxious weed, planting is restricted and non-invasive grasses are used in its place.

How to Identify

Look for dense tussocks of narrow, inrolled, often thread-like leaves and open, drooping panicles of one-flowered spikelets. The telling feature is the seed: a hard, sharp-pointed grain carrying a long, sharply bent and twisted awn that sets Nassella apart from most other tussock grasses. In several species a purple flush colours the panicle before the seed ripens to straw.

Appearance

Size & Dimensions

Height1' - 3'3"

Width/Spread1' - 2'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Spring Summer

The airy seed panicles appear from late spring into summer, mainly May to July in the Northern Hemisphere and November to January in the Southern. Panicles open above the foliage and shed awned seed over several weeks. Dried straw-coloured heads often persist afterwards.

Detailed Descriptions

Flower Description

Purplish to straw

Foliage Description

Green to grey-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam sand rocky clay

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Nassella grows in full sun on free-draining soils of low to moderate fertility and tolerates heat, wind, and extended drought once established. Most species sit in roughly USDA zones 7 to 10 and prefer neutral to slightly alkaline ground, pH about 6.0 to 7.5. Plants need little water or feeding and grow weakly in wet or heavily shaded sites. Because many species self-seed freely, spent panicles are often removed before seed drops. N. trichotoma and N. neesiana are prohibited or restricted in Australia and several other regions, with their sale and movement controlled under noxious-weed law.

Pruning

Dead blades are combed or cut out in late winter before new growth begins to keep tussocks tidy. Taking off spent flower heads before the seed ripens limits unwanted self-seeding. Old clumps can be cut back hard in early spring to renew the foliage.