Hawthorn

Hawthorn (lat. Crataégus) – a genus of deciduous, sometimes semi-evergreen shrubs or small trees in the Rose family (Rosaceae). From a botanical standpoint it is a rather complex genus, numbering 100-200 species, many valuable species among which are still unknown.

Widely distributed in temperate regions of the Northern Hemisphere between 30° and 60°, mainly in North America and Eurasia. In nature they grow solitary or in groups in shrub thickets, on clearings, in cuttings, at forest edges, on screes, sometimes in sparse forests. They do not grow under a dense tree canopy. They occur from sea level up to the upper limit of forest vegetation in mountains. Lifespan 200-300 (400) years.

The name derives from the Greek word «κραθαιος», which translates as «strong». The name reflects the hard wood or the plant's ability to live a long time.

Members of the genus are predominantly deciduous, less often semi-evergreen trees or shrubs reaching 3-5 (10-12) m in height with a rounded, globose or ovoid crown, often asymmetrical.

Bark gray or brown, cracked or unevenly ribbed, sometimes peeling in small plates. Branches straight, less often zigzag or pendulous, sturdy. Young shoots purplish-red, glabrous or densely pubescent to felted. Pith of shoots rounded, toothed at the edges, from white to light green.

Most species have numerous thorns, which are modified shortened shoots that grow at the same time as the leaves from axillary buds on the lower part of the shoots a year earlier than the corresponding buds on the upper parts of the shoots. Thorns reach 0.5-1 cm in length, sometimes 6-7 (10) cm, are leafless, less often leafy. Shoots rarely end in a thorn. Buds grow to the side of the thorn or near its base, less often on both sides of the thorn.

Leaf buds ovate-round, oblong or conical, obtuse, less often acute, 2-10 mm long.

Scales 4-6, arranged spirally, light or dark brown with a carmine tint, often with a lighter margin at the edge, glabrous, shiny, rarely hairy or ciliate at the margin. Leaf arrangement spiral, often crowded at the tips of shoots. Leaves ovate or obovate, sometimes round, elliptic or rhombic, 1-12 cm long, densely pubescent or glabrous, felted beneath, petiolate, sometimes nearly sessile. Blade entire, pinnately lobed, lobed or dissected. Margins deeply and coarsely toothed or serrate, sometimes entire. On long shoots leaves are larger and more deeply lobed than on short ones. Stipules in most species fall off early. In autumn leaves of many species turn orange, golden and purple. In some species leaves remain on the plant for a long time without changing color and fall green or brown.

Inflorescences corymbose, compound, sometimes umbel-like, solitary or many-flowered, located on short lateral shoots of the current year. Axes of pedicels, inflorescences, hypanthia, and sepals glabrous, densely pubescent, less often felted. Flowers small, 1-2 cm in diameter, 5 petals, white (sometimes pink or red), rounded, less often with a short claw. Sepals 5, erect, reflexed or spreading, deciduous or persistent in fruit. Stamens 5-20; anthers white, yellow, pink or purplish-red; styles 1-5, with capitate stigma, often with tufts of hairs at the base. The ovary is formed from 1-5 carpels, which are fused dorsally with the hypanthium and remain almost or completely free on the ventral side. Flowers contain dimethylamine (a colorless gas with a strong smell of fish). Blooms in spring or early summer.

Begins to bear fruit in the 8-10 (15)th year after planting. Fruits – small pome-like fruits formed from the gynoecium surrounded above by the hypanthium. They reach 0.5-4 cm in length, pear-shaped, globose or elongated. Ripen in September – October. Inside the fruit are one or several (up to 5) three-sided large pyrenes, located near the calyx at the top of the fruit and covered by the flesh. The pyrenes have a very hard stony shell, brownish or yellowish, keeled or compressed laterally, smooth, dented, ribbed, or pitted. Fruit color depends on species and cultivar, ranging from pale orange-yellow to red or almost black. Size also depends on cultivar and species, from 0.5-0.7 cm to 4 cm in diameter.

Hardiness zone: 5b

Location: Undemanding regarding terrain and soil. However, they grow better on moderately moist, deep, well-drained, heavy fertile soils. Responds well to lime in the soil. In cultivation the plant is undemanding, winter-hardy and light-loving. Tolerates shading and urban conditions.

Planting: young plants tolerate planting easily. Planting is usually done in early spring or late autumn, but can also be done in summer while in leaf. Planting hole depth should be at least 60-70 cm. Spacing between plants – 1-2 (3) m. Soil mix: humus, leaf soil, peat-compost, sand in proportion 2:2:1:1. At planting it is recommended to add 300-400 g of phosphorite flour and 4-5 kg of lime.

Care: it is recommended to water once a month – 10-12 liters per plant. In dry periods watering should be doubled. In spring you can fertilize with nitroammophoska or Kemira-Universal at 120 g/m². Before flowering it is recommended to feed with diluted manure at a ratio of 1:10 in the amount of 8 l per adult plant.

Pruning: tolerates clipping and shaping well. Has strong shoot-forming ability.

Diseases: powdery mildew, rust, gray, white and brown leaf spots.

Pests: apple-shaped scale insect, acacia false scale.

Propagation: propagated by seeds, root suckers, grafting. For seed propagation long stratification is required (7-8 months). With autumn sowing in open ground not all seeds germinate and the germination period is quite long. In the first year 20-30% of seeds germinate. In subsequent years the germination percentage increases. Germination percentage significantly increases with scarification. When seeds germinate the ovate or elliptical cotyledons emerge above the soil. They are fleshy, glabrous, petiole short (4-13 mm). The hypocotyl part of the seedling glabrous, 1-6 cm long, reddish. First leaves alternate, smaller than normal and with less intensely and less deeply incised blades. In the first two years seedlings grow slowly, afterwards growth gradually increases reaching 7-20 cm per year. Up to 6-8 years of age annual increment is 30-40 (60) cm per year and then slows down again.

It roots poorly from cuttings. Vegetatively propagated by root suckers and layering. Cultivated forms are propagated by grafting. Common hawthorn or one-pistil hawthorn are used as rootstocks.

Uses: a good nectar plant. Wood is used for tool handles, household items, etc. Fruits are used in medicine, eaten fresh and used for making wine, jam, compote. Ground dried fruits are used in baking confectionery and bread. Can be used for bonsai. Widely used in horticulture due to attractive leaves, numerous flowers and bright fruits. Used for hedgerows, in ornamental groups in landscape parks, for stabilizing banks and gullies. Widely used as rootstock for apple, medlar, pear and quince.