Arabis or Rockcress

The origin of the name is not exactly known. Possibly from 'Arabia' — Arabia, a plant of sandy or rocky places; or from the Greek word 'arabos' — scraping.

The genus includes more than 100 species, widely distributed from Arctic to tropical latitudes of Europe, Asia and South America. Annual or perennial plants with trailing and rooting stems. Leaves entire, densely pubescent. Flowers white, pink, lilac or yellowish up to 1,5 см in diameter, simple or double, in small rather dense racemose inflorescences. Fruit — a linear silique with flat, sometimes winged seeds.

Арабис альпийский — Arabis alpina L. = Arabis flaviflora Bunge

In the wild it grows in the Polar Urals, the Far East, northern Scandinavia, the highlands of Western Europe and North America.

A perennial up to 35 см tall. Generative shoots ascending, vegetative ones very branched, pressed to the ground, in the form of thin runners forming cushion-like tufts that do not die back in winter. Basal leaves oval, stem leaves cordate-sagittate, stem-clasping, grayish. Flowers white or pink up to 1 см in diameter, fragrant, gathered in a racemose inflorescence up to 5 см long. Blooms in April — May for 25-30 days. Sets fruit in July. Fruit — a silique.

Garden form schneehaube (f. schneehaube) 10-25 см tall. Flowers white, up to 2 см in diameter, gathered in a racemose inflorescence up to 15 см long. Blooms in April for 25-30 days.

There is also a double variety (var. florе-pleno hort.), morphologically little different from the original, but its inflorescences are significantly larger and resemble wallflower inflorescences. Flowers up to 2 см in diameter. Blooms abundantly from early May to mid-June.

Арабис мхообразный — Arabis bryoides Boiss.

Native to the mountains of Yugoslavia, Greece and Albania, where it grows at subalpine and alpine levels.

A cushion-forming perennial 5-10 см high. Leaves woolly-pubescent, ciliate at the margin, small, oval with an acute tip, gathered in rosettes. Flowers white with 6-7 мм petals in a loose umbel of 3-6, appearing in spring. Requires a sunny position in rockery crevices. Soil should be calcareous, poor, dry and well drained. Needs an airy dry winter cover. Sow seeds in spring; seedlings appear at 10-16 °С within a month. Divide plants in autumn; propagate by green cuttings in early summer.

Арабис выбегающий — Arabis procurrens Waldst. & Kit.

Occurs in the Balkans.

A groundcover plant with small rosettes and inconspicuous flowers, 10-12 см tall. Extremely undemanding. Forms dense tufts very quickly. Good for stabilizing slopes. Hardy, but in snowless winters a covering of conifer boughs is desirable. Propagated, as a rule, by cuttings in early spring or autumn.

An interesting cultivar is ' Variegata' with white-striped leaves. In the center of the small leaf rosettes with a white margin, clusters of purple buds appear in spring. At first they are sessile, without petioles, later opening on stems 5 to 10 см tall. The purple coloration fades and is replaced by white in the flowers.

Арабис кавказский — Arabis caucasica Schlecht. = A. albida.

Some botanists consider Arabis caucasica to be a variety of Arabis alpina.

Grows in the Caucasus, Crimea, the mountains of Central Asia, the Mediterranean and Asia Minor. A perennial plant reaching 30 см in height at flowering time. Prostrate shoots root easily. Differs from Arabis alpina by its more hairy leaves. Leaves small, oblong, coarsely toothed at the margin, gray-green from dense white pubescence. In mild winters the leaves of vegetative shoots persist. Flowers up to 1,5 см in diameter, white, gathered in racemose inflorescences up to 8 см long. Blooms abundantly from early June for about a month, with individual inflorescences appearing throughout the summer. Fruit — a narrow long capsule. In cultivation since 1800.

Арабис проломниковый — Arabis androsacea Fenzl

Native to the rocky slopes of the mountains of Turkey, where it grows at 900-2300 м.

A cushion-forming perennial 5-10 см high. Leaves small, oval with an acute tip, gathered in rosettes. Flowers white in a loose umbel appearing in summer. Requires a sunny position in rockery crevices. Soil should be poor, dry and well drained. Needs an airy dry winter cover. Sow seeds in spring; seedlings appear at 10-16 °С within a month. Divide plants in autumn; propagate by green cuttings in early summer.

Арабис реснитчатолистный — Arabis blepharophylla Hook. & Arn.

Native to the mountains of California, where it grows at about 500 м.

A perennial 8 см tall with a clump diameter up to 25 см. Leaves gray-green, flowers dark pink. In cultivation, commonly grown cultivars are: 'Fruhlingszauber' — with pink flowers and small leaves, 20 см tall; 'Rote Sensation' — with bright pink flowers, more elongated leaves, 20 см tall. Hardiness zone for this species is 7. Winter covering is mandatory.

Site: requires open, sunny locations; they can also grow in partial shade, but in a sunny spot the plant is more compact and flowers more profusely, and it spreads rapidly, covering a large area.

Soil: not wet sites; loose, sandy, well cultivated soils.

Care: in the conditions of northern Ukraine on exposed sites they require light winter covering. Care is the same as for other perennials. Pay particular attention to weeding. Arabises spread quickly sideways and can smother neighboring plants, so it is necessary to shorten overly vigorous and outward-growing shoots, which significantly improves flowering the following year. They perish from winter waterlogging. With early snowmelt they suffer from drying out of shoots — shading is required.

Propagation: by seed; double forms — by dividing the clump and by cuttings. Sow seeds in spring or before winter; seedlings flower in the second year. Divide 3-4 plants, from which up to 20 well-developed "divisions" can be obtained. Sometimes clumps are divided without lifting, by separating a part. Planting is done in spring or autumn (August — first half of September), maintaining a spacing of 30-35 см between plants.

Cutting is carried out from mid-May to early June. Cuttings are taken from the upper part of the green shoots of the current year 6-8 см long. Remove the lower 2-3 leaves and plant them into prepared beds in that state. Shade and sufficient watering are mandatory for planted cuttings. When trimming tufts, all cut shoots are usually used for cuttings. Rooting usually occurs within 2-3 weeks. Rooted cuttings are planted in their permanent place in the same year in late August — September.