Crataegus

Hawthorn (Crataegus) is a large genus of shrubs and trees in the family Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe, especially the Common Hawthorn C. monogyna, and the unmodified name is often so used in Britain and Ireland. However the name is now also applied to the entire genus, and also to the related Asian genus Rhaphiolepis.

They are shrubs and small trees growing to 5-15 m tall, characterized by their small pome fruit and thorny branches. The bark is smooth grey in young individuals, developing shallow longitudinal fissures with narrow ridges in older trees. The fruits are sometimes known as "haws", from which the name derived. The thorns grow from branches, and are typically 1-3 cm long. The leaves grow spirally arranged on long shoots, and in clusters on spur shoots on the branches or twigs. The leaves themselves have lobed or serrate margins and are somewhat variable shape.

The number of species in the genus depends on taxonomic interpretation, with numerous apomictic microspecies; some botanists recognise a thousand or more species, while others reduce the number to 200 or fewer.

Hawthorns provide food and shelter for many species of birds and mammals, and the flowers are important for many nectar-feeding insects. Hawthorns are also used as food plants by the larvae of a large number Lepidoptera species.

Many species and hybrids are used as ornamental and street trees. The Common Hawthorn is extensively used in Europe as a hedge plant. Several cultivars of the Midland Hawthorn C. laevigata have been selected for their pink or red flowers. Hawthorns are among the trees most recommended for water-conservation landscapes.

Culinary use
The fruits of the species Crataegus pinnatifida (Chinese Hawthorn) are tart, bright red, and resemble small crabapple fruits. They are used to make many kinds of Chinese snacks, including haw flakes and tanghulu (糖葫芦). The fruits, which are called shānzhā (山楂) in Chinese, are also used to produce jams, jellies, juices, alcoholic beverages, and other drinks. In South Korea, a liquor called sansachun (산사춘) is made from the fruits.To the western palate, drinks made from the fruits taste similar to barbecue sauce.

The fruits of Crataegus pubescens are known in Mexico as tejocotes and are eaten raw, cooked, or in jam during the winter months. They are stuffed in the piñatas broken during the traditional pre-Christmas parties known as posadas. They are also cooked with other fruits to prepare a Christmas punch. The mixture of tejocote paste, sugar, and chili powder produces a popular Mexican candy called rielitos, which is manufactured by several brands.

In the southern United States fruits of three native species are collectively known as Mayhaws and are made into jellies which are considered a great delicacy.

The leaves are edible and, if picked in the months of April and May, they are tender enough to be used in salads.

Medicinal use
The dried fruits of Crataegus pinnatifida (called 山楂 or shān zhā in Chinese) are used in naturopathic medicine and traditional Chinese medicine, primarily as a digestive aid. A closely related species, Crataegus cuneata (Japanese Hawthorn, called sanzashi in Japanese) is used in a similar manner. Other species (especially Crataegus laevigata) are used in Western herbal medicine, where the plant is believed to strengthen cardiovascular function. In recent years, this use has been noted and adopted by Chinese herbalists as well. Hawthorn is also used as an aid to lower blood pressure, and treat some heart related diseases.

Several clinical trials have assessed the ability of hawthorn to help improve exercise tolerance in people with NYHA class II cardiac insufficiency compared to placebo. One trial, at (300mg/day) for 4 to 8 weeks, found no difference from placebo. The second trial, including 78 subjects (600mg/day) for 8 weeks, found "significant improvement in exercise tolerance" and lower blood pressure and heart rate during exercise. The third trial, including 32 subjects (900mg/day) for 8 weeks, found improved exercise tolerance as well as a reduction in the "incidence and severity of symptoms such as dyspnea" and fatigue decreased by approximately 50%.
 * Clinical trials

In the HERB-CHF (Hawthorn Extract Randomized Blinded Chronic HF Study) clinical trial, 120 patients took 450mg of hawthorn extract twice daily for 6 months in combination with standard therapy and a standardized exercise program. "No effects of hawthorn were seen on either quality-of-life endpoint (Tables 1 and 2), or when adjusted for LVEF".

One study, consisting of 1011 patients taking one tablet (standardized to 84.3mg procyanidin) twice daily for 24 weeks, found "improvements in clinical symptoms (such as fatigue, palpitations, and exercise dyspnea), performance and exercise tolerance test, and ejection fraction".

Other uses
The wood of some hawthorn species is very hard and resistant to rot. In rural North America it was prized for use as tool handles and fence posts.

Side effects
Overdose can cause cardiac arrhythmia and dangerously lower blood pressure. Milder side effects include nausea and sedation.

Folklore
The custom of employing the flowering branches for decorative purposes on the 1st of May is of very early origin; but since the adoption of the Gregorian calendar in 1752, the tree has rarely been in full bloom in England before the second week of that month. In the Scottish Highlands the flowers may be seen as late as the middle of June. The saying "Ne'er cast a cloot til Mey's oot" conveys a warning not to shed any cloots (clothes) before the summer has fully arrived and the may flowers (hawthorn blossoms) are in full bloom.

The hawthorn has been regarded as the emblem of hope, and its branches are stated to have been carried by the ancient Greeks in wedding processions, and to have been used by them to deck the altar of Hymenaios. The supposition that the tree was the source of Jesus's crown of thorns gave rise doubtless to the tradition current (as of 1911) among the French peasantry that it utters groans and cries on Good Friday, and probably also to the old popular superstition in Great Britain and Ireland that ill-luck attended the uprooting of hawthorns. Branches of Glastonbury Thorn, C. Oxyacantha, var. praecox, which flowers both in December and in spring, were formerly highly valued in England, on account of the legend that the tree was originally the staff of Joseph of Arimathea.

In Celtic lore, the hawthorn plant was used commonly for rune inscriptions along with Yew and Apple. It was once said to heal the broken heart.

In Serbian folklore, a stake made of hawthorn wood was used to impale the corpses of suspected vampires.

References and external links

 * Photos of Chinese haw berries
 * Key to Crataegus of Western North America
 * Medicinal uses of Hawthorn in Armenia
 * Edible uses of hawthorns at Plants For A Future
 * Crataegus phaenopyrum images at bioimages.vanderbilt.edu

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