Arthraxon hispidus aka Jointhead

Arthraxon hispidus is a grass in the Poaceae family. People call it small carpetgrass, creek grass, or hairy jointgrass. Kew lists tropical Africa as part of its native range. This range includes the western Indian Ocean region and Asia. It also reaches eastern Australia. The grass can live as an annual or perennial. This means it can live for one year or more. Kew links it to tropical climates with dry seasons.

This grass grows fast to about 1.5 feet [0.46 metres] tall. Its many stems may stand upright, lean, or creep along the ground. The round, green stems may have red tones. White hairs cover parts of the stems. Green leaves grow in turn along each stem. Each simple leaf has a sharp tip and a smooth edge. Leaves range from lanceolate to ovate: lance-shaped to egg-shaped. Each leaf has a heart-shaped base that wraps around the stem. White hairs line the leaf edges. The amount of hair varies from leaf to leaf.

The grass blooms from late summer through fall. Flower spikes grow on branched stems and from leaf axils. These axils are where leaves join the stem. Each spike bears small spikelets, pale green to purple in color. The fruit is a caryopsis, or dry grain. Seeds are yellowish or tan. Seedheads can stay through fall and winter. The plant makes many seeds that help it spread. Stems also root at their nodes, or joints, and extend colonies.

Small carpetgrass grows best in moist soil and full sun. It also grows in part shade and copes with wet ground. It forms dense patches by streams, ponds, and lakes. Wet meadows and open ground that has been disturbed also suit it. These traits help explain how it spreads through damp sites. The evidence gives growing needs but no hardiness rating. It confirms no food use and gives no toxicity assessment.

In the United States, this grass is an invasive weed. It may have arrived by chance in the early 1900s. North Carolina State records it in 25 eastern and midwestern states. Its U.S. range runs from New England to Florida and Texas. It grows throughout North Carolina. The worst problems there occur in the Piedmont. Its fast spread means it needs much work to control. North Carolina State advises mowing and pulling small patches before they bloom. It reports that glyphosate-based control works on larger patches. Its main recorded landscape problem is its weedy, invasive growth.