Horseweed is a native annual plant that can grow to a height of over 2 m. When mature, several flowering stems appear at the apex, which branch frequently and create a multitude of tiny composite flowers. In each flower, there are numerous yellow disk florets in the center, which are surrounded by tiny white ray florets. There is no noticeable floral scent. The blooming period can occur any time from midsummer to fall, lasting about 3 wk.

The leaves alternate all around the stem (appearing almost whorled) and differ little in length, creating a columnar effect. The stout central stem is ridged and unbranched, except for the flower stems near the apex. Seeds are tiny and distribution is by wind. The preference of the plant is full sun, moist to dry conditions, and rich fertile soil. However, this plant flourishes in other kinds of soil, including those containing considerable amounts of gravel and clay. This weedy plant is easy to grow and sometimes forms large colonies in favorable disturbed sites. Drought resistance is very good. The plant dies in early September and drydown is rapid.

Stem construction consists of a moderately waxy epidermis. The xylem cylinder has a XPR of 0.92 and a typical stalk diameter of 0.9 cm. The xylem material has a density of almost 675 kg/m3, which is a little light. The pith is a solid spongy inner core that appears to be resilient to rot for many months.

According to estimates, horseweed may have one of the highest yields of all the plants presented here (see Table 1). Projections indicate that 13.3 t/acre can be taken with current cultivation techniques and no engineering of the plant. Another benefit of horseweed is that it flourishes in dry con­ditions and in rough soil such as clay and gravel. It is also an early maturing plant and can be harvested as a fuel as early as September.