Taking an environmentally sensitive approach to pest management
The mention of fall color associated with a woody plant normally conjures up images of trees with leaves vibrantly aglow in fiery hues of yellow, orange and red. In contrast, the fall foliage of hawthorns pales in insignificance to the color provided by the small, abundant fruits of these species. Additionally, unlike foliage color, fruit color tends to persist longer into the fall and early winter, providing extended landscape appeal. Throw in the facts that their flowers benefit pollinating insects and their fruits attract birds, and you have a strong case that hawthorns are under-appreciated as woody ornamental plants.
The hawthorns belong to the genus Crataegus which is a member of the Rosaceae plant family. Its fruits often are referred to as berries, but botanically are classified as pomes. The genus name is derived from the Greek words kratos (strength) because of the great strength of the wood, and akis (sharp) making reference to the thorns of most species. Its common name comes from the old Anglo-Saxon word haguthorn which, literally interpreted, mean "fence with thorns," making reference to its occasional use as a hedge tree.
There are about 75 species of hawthorns native to Missouri. Most are small, thorny trees that, although found throughout our state, especially are prevalent in the Ozarks. Legislation enacted in 1923 designated the white hawthorn blossom as Missouri's state flower. Although the legislation did not mention any species in particular, many consider the honor belongs to downy hawthorn (Crataegus mollis) or dotted hawthorn (C. punctata). Both are small, deciduous trees native to Missouri and bear abundant clusters of white flowers in the spring, followed by small, apple-like fruits in the fall.
In addition to North American, hawthorns are native to temperate regions of the Northern Hemisphere including Europe, Asia and North Africa. Rich in folklore, hawthorns were symbolic of hope in days of old. Ancient Greeks used its branches in wedding processions. In Celtic lore, hawthorns were said to heal the broken heart. In Gaelic folklore, hawthorn trees were thought to mark the entrance to the "otherworld" and were strongly associated with fairies. A rather bizarre belief in Serbian folklore was that stakes made from the wood of hawthorn trees could slay vampires.
Several species of hawthorn have long been prized for their medicinal properties. Even today, herbalists use hawthorn to treat diseases of the heart and blood vessels (e.g. congestive heart failure), chest pain, irregular heartbeat, both low and high blood pressure, atherosclerosis, and high cholesterol. Much of hawthorn's medicinal value is credited to a compound called proanthocyanidin, a flavonoid plant pigment found primarily in its fruits.
Because of the tendency of people to refer to hawthorns as "haws", some confusion relative to their true identity exists. For example. plants with the common names of green haw (Crataegus viridis) and red haw (C. coccinea) are true hawthorns. In contrast, the black haw (Viburnum prunifolium) and possum haw (Ilex decidua) are not.
Black haw is a viburnum that matures into a small tree, but lacks thorns. Its fruits are blue-black in color and its leaves turn an attractive maroon-purple to rose-red in fall. While an attractive landscape plant, it long has been valued for the medicinal properties of its bark which is used primarily to treat gynecological conditions.
Possum haw is a deciduous holly. It also develops into a small tree and bears bright red fruits in the fall. However, unlike hawthorn fruits which are formed in clusters, the fruits of possum haw are borne along its stem. Possum haw has smooth bark which is light-grey in color.
The red haws (Crataegus coccinea, C. pedicellate and C. mollis) are true hawthorns which are useful landscape tree. Most have thorns that may be up to several inches in length. Therefore, it is best to locate the plants out of the way of small children, or where people might walk near them on a frequent basis. They are attractive when used as screens, backgrounds, or as specimens near evergreens. The dark green needles of the latter set off the brightly-colored, red fruits of red hawthorns nicely. The aforementioned downy hawthorn is a red haw with hawthorn's typical white flowers and red fruit, but is considered less thorny than other members of the red haw group.
Those hawthorns that grow into small trees are best located in full sun. They are adaptable to many soil types, ranging from sandy to heavy clay. Among the most durable hawthorns for Midwest landscapes are the Washington hawthorn (Crataegus phaenopyrum), cockspur hawthorn (Crataegus crus-galli) and the green hawthorn mentioned above. Washington and green hawthorns tolerate soils with a wide range of acidity, but the cockspur hawthorn often develops iron chlorosis when planted in alkaline soils. Hawthorns are not suitable for wet, poorly-drained sites.
The Washington hawthorn is a very popular hawthorn for landscapes and one of the most tolerant of urban conditions. A small tree, it matures to a height of about 35 feet with nearly an equal spread, and blooms late in spring with clusters of white flowers. Large clusters of orange-red fruits persist from early fall until cold temperatures turns them black for the winter, or until birds consume them. Significant cultivars of Washington hawthorn include 'Clark' (heavily fruited), 'Fastigiata' (columnar growth habit) and ''Princeton Sentry' (fewer thorns and very vigorous).
The cockspur hawthorn forms a large shrub or small tree. It has beautiful glossy, dark-green leaves. Its thorns are quite long and can be threatening. However, a thornless cultivars have been developed but can be difficult to find in commerce. Two cultivars to look for include 'Thornless Cockspur Hawthorn' and 'Cruzam' (a.k.a. 'Crusader Hawthorn'). The latter is very disease resistant.
The best of the green (a.k.a. southern) hawthorns is a cultivar called 'Winter King.' This wide-spreading small tree is vase-shaped and has fewer thorns than the species. It has added winter appeal since its bright, reddish-orange remain attractive until temperatures become very cold. It is more disease resistant than its species and has the added benefit of being nearly thornless.
Lavalle hawthorn (Crataegus x lavallei) matures into a small tree about 15 to 25 feet in height. Quite tolerant of city conditions, it has very attractive glossy green foliage. 'Crimson Cloud' is a cultivar with bright red flowers and fine-textured leaves. Among the most cold-tolerant hawthorns is the Toba hawthorn (Crataegus x mordenensis). A selection from it marketed as the cultivar 'Snowbird' is rated hardy to zone three. 'Snowbird' has attractive, glossy foliage, small double white flowers and bright red persistent fruits. It has a mature height of about 20 feet.
Cedar hawthorn rust is the most common disease problem of most hawthorns. Symptoms include small yellow specks on upper leaf surface that gradually enlarge into brightly colored orange spots later in the season. Although the disease detracts from their ornamental value, it rarely kills hawthorns. Lace bug is a common insect pest of the hawthorns. It tends to feed on the lower surface of leaves, sometimes causing them to turn brown by late summer.
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REVISED: November 3, 2020