Crataegus is a plant genus that is part of the Rosaceae family. It contains between 200 and 1,000 species, depending on the classification system used to describe the plants. Most are deciduous trees or shrubs that are native to North America and parts of China. They have thorny branches, white flowers, and fruits which resemble small red apples. This genus of plants is vulnerable to insect damage and fungal diseases.
The name Crataegus is a Greek word meaning "flowering thorn," which aptly describes the species within this genus. The common name for this genus is hawthorn or thornapple. Some of the species in this genus include C. pinnatifida, C. monogyna, and C. intricata.
Several trees in this genus have been used in traditional Chinese medicine for their potential health benefits. Herbal medicines derived from the Crataegus pinnatifida tree are used to aid in digestion and improve heart function. It is believed that the extracts are also rich in flavonoids, which are potent antioxidants.
There are several species which are used in landscaping, including Crataegus monogyna. It grows about 33 feet (10 m) in height and has a spread of 25 feet (8 m). This species has a rounded form and is deciduous. The glossy green leaves are deeply lobed and are attached to branches that are densely covered with thorns. White fragrant flowers bloom in late spring, and are followed by small red fruits.
Most species in this genus grow well in most soil types. Whether it is loam, sand, or clay, as long as the soil is well-draining, the Crataegus shrub or tree will do fine. The pH of the soil isn't a concern either, since most species do well in acidic or alkaline conditions. Also, this genus can grow in areas with direct sunlight or partial shade.
The main concern with growing plants in the Crataegus genus is plant diseases, particularly fireblight. Fireblight is a bacterial infection caused by the bacterium Erwinia amylovora. It produces a brown watery substance that exudes from the branches and trunk. Leaves and fruits become wilted and appear brown or scorched.
Another concern is insect damage from aphids, caterpillars, and gall mites. Aphids and caterpillars feed on the leaves of the tree, while gall mites distort stems and leaves by forming clumps of sugary material that harden into knobs or bumps. Aphids also leave a sticky residue on the tree that attracts mold.
