| Neutral | htop | On Oct 18, 2005, htop from San Antonio, TX
(Zone 8b) wrote:Common Cocklebur (Xanthium strumarium var. glabratum) is a weedy, taprooted, wetland native plant that is widely distributed throughtout the USA. It is not native to 11 states. It can be found growing around watering holes, arroyas, playas, cropland (especially corn fields), fallow fields, degraded meadows, stabilized areas of beaches and sand dunes, the floodplain zone of rivers and ponds, vacant lots and disturbed areas. It prefers a loamy or sandy and moist to mesic (neither to moist nor too dry) soil.
Common cocklebur leaves are alternate, toothed and lobed. The male and female blooms, which are both inconspicuous, occur on the same plant. The female bloom appears at the leaf axil and the male bloom producing only pollen occurs in dense clusters at the ends of the stems. Cockleburs are short-day plants; that is, they only flower when the nights are long. In North America, cockleburs they bloom during late summer and in the early fall when the days are shorter and the nights longer. However, some plants may bloom a little earlier or later. They will not bloom near a street light. The plants are wind pollinated and lack a floral scent. The very conspicuous, hard, spiny, football-shaped fruits have many spines and contain 2 compartments that each house 1 seed. One of the seeds in each bur may germinate the following year with the other seed taking at least 2 years to germinate. The burs stick to fur and clothing and can be very difficult to extract. Often they form tangled clots in the fur of animals which have to be cut out.
Young seedlings give off toxic chemicals that can inhibit germination of other species of plants and/or kill off their seedlings. The toxicity level lessens as the plants mature. All classes of livestock may be poisoned by the cocklebur. Seedlings and seeds are the most toxic parts of the plants. Usually, livestock do not eat the seeds. However, if furnished hay or cottonseed feed contaminated with cocklebur serious problems and even death may occur. Pigs eating a sufficent amount of young plants may be poisoned. It does Deer occasionally eat the upper half of mature plants before the bur-like flowers form. Sometimes horses and cattle eat the mature plants with the bur-like flowers. This can lead to obstruction of the gastrointestinal tract. The purple finch and Franklin ground squirrel eat the seeds with no ill affects. |
