Longspine sandbur  (Cenchrus longispinus)

Longspine sandbur, a loosely clumped grass, is usually a summer annual in California, but in other regions can be a biennial or perennial. In California, it is found in the southern Sacramento Valley, San Joaquin Valley, southwestern regions, Mojave Desert and Modoc Plateau to about 3000 feet (900 m). Longspine sandbur favors sandy or well-drained soil. Longspine sandbur grows on agricultural land and in other disturbed areas. It is difficult to distinguish from southern sandbur and field sandbur. All of these species are aggressive and can invade and colonize an open, disturbed site. Immature sandburs provide good forage for livestock. However, when they mature they develop fruit with stiff spines that can injure the mouths of animals and the hands and feet of people.

Habitat

Open disturbed sites in fields, orchards, vineyards, croplands (especially alfalfa), ditch banks, roadsides, and other unmanaged, disturbed areas.

Seedling

Seedlings closely resemble those of barnyardgrass. The cotyledon (seed leaf) is flattened and has a purplish tinge at the bottom. The most distinctive characteristic for seedling identification is a spiny bur (see “Mature plant” section), from which the young plant emerged. It may be found by digging carefully around the roots.

Mature plant

Plants often form large mats and can grow to 2 feet (0.6 m) in length. Branched stems grow erect or spread, are flattened in cross-section, often bend abruptly toward the base, and have loose spikes of spiny burs at maturity. Each bur contains one to three seeds. A seed germinates from within a bur. Therefore, the bur a seedling grew from can be found around the root system of the young plant. Sheaths are open, usually hairless, and their margins are membranous and sometimes lined with a few hairs. Leaves are flat, sometimes folded, with a hairless upper surface, and fold in the bud.

Collar region

The collar is narrow and lighter in color than the rest of the sheath and on occasion has sparse, long hairs on its margin. The ligule consists of a fringe of hairs.

Flowers

Flowering takes place from July through September. The main flower stalk axis is wavy and contains yellowish green, spiny burs. Burs consist of flower clusters enclosed in spiny modified leaves (bracts). Up to 50 burs may occur on a spike but generally there are 40 or fewer. The spike is partially enclosed by a leaf sheath. Burs turn light brown when they mature. Burs disperse in many ways such as by clinging to animals, shoes, clothing, tires, machinery, and floating on water.

Reproduction

Reproduces by seed.

Related or similar plants

• Barnyardgrass, Echinochloa crus-galli, seedling
• Southern sandbur, Cenchrus echinatus
• Field sandbur, Cenchrus spinifex

More information

• Grass ID illustration
• Calflora's distribution map
• For agriculture: UC IPM Pest Management Guidelines