Heracleum is a plant genus that is part of the Apiaceae family. It contains about 70 species of perennial herbs that are native to Europe, Asia, North America, and Africa. These plants rise high above the ground on narrow stems and feature large flower clusters. Landscapers use this group of plants along borders and in overgrown areas of a yard. Some common problems associated with the Heracleum genus include leaf spot and stem rot.
The name of this genus is derived from the Latin word Herâclêus, which translates to "of or belonging to Hercules." It is believed that the mythological Hercules used these plants as medicine. The common name for plants in the Heracleum genus is cow parsnip, since these species are similar in appearance to parsnips and are consumed by cattle. Some species are known as hogweed or giant hogweed, including Heracleum mantegazzianum.
Cow parsnip is typically grown in Canada and the United States. Heracleum sosnowskyi is distributed from the Caucuses to the Baltic states in Europe, while Heracleum persicum is grown in Iran. There are a few species located in Africa, including Heracleum sphondylium.
These plants are very tall. H. maximum typically grows 3-10 feet (1-3 m) in height and features large rough leaves, roughly 18 inches (45 cm) wide. Each leaf is divided into three segments and features toothed edges. The long, narrow stems are hollow and hairy.
Atop the narrow stems are white to cream colored flowers that are fragrant. Each flower has five petals that are roughly 1/3 inch (1 cm) in length. They sprout in clusters that are arranged in umbels. An umbel is a flower arrangement in which several similarly sized, erect flower stalks sprout from the same point on the stem. The flowers typically bloom in mid-summer.
H. maximum can grow in several types of soil including loamy, sandy, and clay. It does well in shaded areas and can tolerate cold winters. It can survive in hardiness zones three and higher.
A common problem that affects H. maximum is leaf spot, which is a fungal disease. It is characterized by black or brown spots on the leaves and dropping leaves. The fungal spores typically reside in dead leaves and plant debris during the winter. During the spring time, the spores are carried by wind and water splashes and deposited onto the leaves of H. maximum. A common preventative step is to remove all dead plant material from the ground before the start of the growing season.