Box grass or Knottybutt grass
SCIENTIFIC NAME: Paspalidium constrictum
CATEGORY: C4 perennial
IDENTIFICATION TIPS
- A tufted, erect to spreading, warm season perennial to 60cm tall and with hairy, thickened, knotted stem bases
- Leaves dull-green to blue-green with a prominent midrib. Stems mostly covered in dense short hairs. Nodes covered with soft fine hairs, with a few long hairs
- Seedhead is a narrow primary axis of racemes to 35cm long, with the branches pressed against the main axis. Each branch ends in a short bristle
- Spikelets have a distinct constriction along their length
- Flowers throughout year, but major flowering is in summer and autumn following rain
CLIMATIC & SOIL REQUIREMENTS
- Widespread on lighter soils (sandy loam to clay loam); rarely on clays
- More common on fertile soils where moisture is high
- Usually found under tree canopies and where it is protected from grazing around fallen timber
- Very drought tolerant and slightly frost tolerant
GRAZING & NUTRITIONAL VALUE
- High grazing value
- Digestibility ranges from 35-56% - from one trial only at Cobar
- Crude protein 11-15.5%
MANAGEMENT STRATEGIES
- Usually only a minor component of pastures
- Dry matter yields are low, but it is highly palatable and regarded as useful forage even after it has hayed off
- On poor soils it forms a slender wiry plant, but forms a dense leafy tussock on moister, more fertile sites
- The bulk of growth is produced in summer and autumn, but it will produce a green pick throughout the year in all but the driest times
- Persists best under rotational grazing. It rapidly regenerates when stock are excluded after heavy grazing, as its buds are below ground level and protected from damage
SIMILAR PLANTS
- Slender panic (Paspalidium gracile) is common and very difficult to distinguish; nodes are usually hairless or covered with minute soft hairs and the seedheads extend well beyond the leaves
- The spikelets of warrego summer grass (Paspalidium jubiflorum) and bent summer grass (Paspalidium aversum) don’t have constrictions their length. The latter species has weak and easily compressed stems that often root at the lower nodes
(Plant: L McWhirter)
