The cockleburr is a hitchhiker. The seed pod is a burr with hooked spines. It tangles the fur of animals unfortunate enough to brush against the dying plant.

Male flower heads occur at the ends of branches, and the female flower heads occur in the lower parts of these branches. The female heads develop into hard, woody, spiny burrs. These burrs are oval shaped, brown, 20-30 mm long, and covered in hooked spines.

Cockleburr is an annual species that generally germinates from late winter to late summer. Germination often occurs after rainfall and irriga­tion. The burrs contain two seeds, one larger than the other. The larger seed has limited dormancy and usually germinates in the season it is produced or the following season. The smaller seed has a longer period of dormancy. The plant grows in a wide range of soil types.

Stem construction consists of a moderately waxy, dark brownish-red epidermis. The xylem cylinder has an XPR of 0.46 and a typical stalk diameter of 1.75 cm. Xylem material has a density of almost 390 kg/m3, which corresponds to a corkwood. The pith is a solid spongy inner core that appears to be resilient to rot for many months.

Although an SSP, cocklebur does not have good technical character­istics. In particular, the low XPR and density indicate that there is not much dry matter in this stalk. In addition, the burrs are a hazard, or at least an inconvenience, to the workers who must deal with this material. Surely the most serious disadvantage is that it is rated a Class C noxious weed, indi­cating that the introduction of burrs must be prevented.