Chilean needlegrass

Nassella neesiana
Grass
Basal
Simple
Brown
Green

A densely tufted long-lived grass with upright or arching stems growing 30-120 cm tall. Its linear leaves (1.5-5 mm wide) are either flat or rolled inwards. Its seed-head is a loose, and either upright or nodding, branched panicle (5-40 cm long) with many flower spikelets that are borne singly. These flower spikelets are elongated in shape (10-22 mm long) and topped by a large twisted awn (45-80 mm long). The mature seed has a small membranous crown-like structure (about 1 mm long) where the awn attaches to the top of the seed. This species also produces 'stem seeds' within the leaf sheaths.

Common names 
Also known as: Chilean needlegrass, Chilean needlegrass, Chilean speargrass, Uruguayan tussockgrass,
Family 
Poaceae
Deciduous 
No
Flowering time 
Spring - Autumn
Native/Exotic 
Exotic
Origin 
Native to South America.
Notifiable 
No
State declaration 
Category 3 - Must not be distributed or disposed. This means it must not be released into the environment unless the distribution or disposal is authorised in a regulation or under a permit.
Council declaration 
As per State Declaration
Known distribution 

Widely naturalised in south eastern Australia (i.e. in eastern and southern New South Wales, in the ACT, in many parts of Victoria, in Tasmania and in south-eastern South Australia). Also recently recorded from a few locations in sub-coastal south-eastern Queensland. Also naturalised overseas in Europe (i.e. in the UK and southern France) and New Zealand.

Habitat 

A weed of pastures, grasslands, open woodlands, parks, roadsides, disturbed sites, waste areas and creekbanks in temperate, semi-arid and sometimes also drier sub-tropical regions.

Habit 

A tussock-forming, long-lived (i.e. perennial), grass with upright (i.e. erect) or arching flowering stems (i.e. culms) usually growing 30-120 cm tall.

Impact and control methods 

Chilean needlegrass (Nassella neesiana) is one of the Weeds of National Significance (WoNS) in Australia, and is regarded as an environmental weed in Victoria, south-eastern New South Wales, the ACT, Tasmania and South Australia.

Stem and leaves 

The stems have 3-4 swollen joints (i.e. nodes) that are sometimes covered in small soft hairs (i.e. they are downy). The leaves consist of a leaf sheath, which encloses the stem, and a spreading leaf blade. The leaf blades (10-30 cm long and 1-5.5 mm wide) are either flat or somewhat rolled (i.e. involute or convolute) and either hairless (i.e. glabrous) or sparsely hairy (i.e. puberulent). Where the leaf sheath meets the leaf blade there is a small membranous flap (i.e. eciliate ligule) 0.5-4 mm long, which has tufts of hairs at either side.

Flowers and fruits 

The seed-head (5-40 cm long) is a loose, upright (i.e. erect) or nodding panicle. The numerous flower spikelets are borne singly and each contains a single floret and two purplish-coloured bracts (i.e. glumes). When mature this floret separates from the bracts (i.e. glumes) which remain on the seed-head (i.e. inflorescence) for some time afterwards. The flower spikelets (10-22 mm long) are elongated (i.e. lanceolate) and cylindrical (i.e. terete) in shape and are topped with a very long awn. Flowering occurs from late spring through to autumn, but is most common during the summer months. Two types of seeds are produced by this species. Normal seeds are produced on the main seed-head (i.e. inflorescence). These seeds (6-10 mm long) have a sharpened, hairy tip (i.e. pilose callus) at one end and a twisted and bent awn (45-80 mm long) at the other end. Where the awn attaches to the seed there is a small membranous, crown-like structure (i.e. corona) about 1 mm long that is surmounted with tiny hairs (i.e. a coma). The other type of seed produced is called a 'stem seed' (i.e. cleistogene). These much smaller seeds are produced at the joints (i.e. nodes) of the flowering stems (i.e. culms) and are concealed in the leaf sheaths.

Reproduction and dispersal 

This species reproduces via two types of seeds. Aerial seeds are produced in its seed-heads and 'stem seeds' (i.e. cleistogenes) are produced in its leaf forks.The aerial seeds readily become attached to animals, clothing and vehicles. Both types of seeds may also be dispersed in contaminated agricultural produce (e.g. fodder) and soil.

Similar species 

Chilean needlegrass (Nassella neesiana) is very similar similar to lobed needlegrass (Nassella charruana), cane needlegrass (Nassella hyalina), Texas needlegrass (Nassella leucotricha) and short-spined needlegrass (Nassella megapotamia). These species can be distinguished by the following differences: Chilean needlegrass (Nassella neesiana) has seeds with relatively long awns (more than 45 mm long) and a short corona (less than 1.5 mm long). Its flower spikelets are relatively large (10-22 mm long) and it produces stem seeds (i.e. cleistogenes).lobed needlegrass (Nassella charruana) has seeds with relatively long awns (more than 45 mm long) and a long corona (5-6 mm long). Its flower spikelets are relatively large (16-20 mm long) and it does not produce stem seeds (i.e. cleistogenes).cane needlegrass (Nassella hyalina) has seeds with relatively short awns (20-45 mm long) and a short corona (less than 1.5 mm long). Its flower spikelets are relatively small (5-12 mm long) and it produces stem seeds (i.e. cleistogenes).Texas needlegrass (Nassella leucotricha) has seeds with relatively long awns (more than 45 mm long) and a moderately-sized corona (1.5-2.5 mm long). Its flower spikelets are relatively large (10-17 mm long) and it produces stem seeds (i.e. cleistogenes).short-spined needlegrass (Nassella megapotamia) has seeds with relatively long awns (more than 45 mm long) and a short corona (less than 1.5 mm long). Its flower spikelets are relatively small (7-10 mm long) and it does not produce stem seeds (i.e. cleistogenes). Several other introduced grasses are relatively similar. These include serrated tussock (Nassella trichotoma), Mexican feathergrass (Nassella tenuissima), broad kernel espartillo (Amelichloa caudata), narrow kernel espartillo (Achnatherum brachychaeta), plumerillo (Jarava plumosa) and Uruguayan ricegrass (Piptochaetium montevidense). None of these species have collars (i.e. coronas) on their seeds.In addition, several native tussock-forming grasses can look similar (e.g. Poa spp. and Austrostipa spp.). However, these species either lack ligules on their leaves, or have ligules that are fringed with hairs, and they also do not have collars (i.e. coronas) on their seeds.Note: This page only covers those grasses that are commonly confused with this species. For a more in-depth key to all of the grasses present in Australia, see the AusGrass: Grasses of Australia CD-ROM or Flora of Australia, Volumes 43 and 44.