Hairy
rockcress (Arabis hirsuta)
The specific name hirsuta means "with rather coarse or stiff hairs" in botanical Latin. Linnaeus described hairy rock cress for science in 1772.[1] Members of North American Arabis sp. have recently been consolidated with genus Boechera.[2]
There are both North American and European varieties of Arabis hirsuta in
Range
Arabis hirsuta is a relatively common species distributed
across most of the
Climate, elevation
Located on moderately moist to dry sites. Climatic zones can vary from less than 18 inches of annual precipitation up to 60 inches in wetter climatic zones.[6] Elevation is from sea level to about 1500 feet.[7]
Local occurrence
Occurs in grassland balds, on
shallow soils with bedrock outcrops located in the Puget Lowland of Washington
(primarily northern portion) and the adjacent Georgia Depression of B.C.
Counties:
Habitat preferences
Moist to dry, usually calcareous, open situations: open woods, stream banks, ledges, cliffs, bluffs, and floodplains4. It occurs frequently in disturbed habitats. Dunes and dry banks7, rocky/chalk, limestone slopes[9] and gravelly native prairie1. Plants seem to be more abundant where grazing is light1.
Plant strategy type
Hairy rock cress is either biennial (lives for two years) or perennial (long-lived and blooms each year)1. It is a stress-tolerator (drought-resistant[10], often growing in nutrient poor soils). In stressful environments it develops a system of rootstocks that allow it persist in inhospitable sites. Hairy rock cress also displays a weedy tendency, colonizing recent road cuts or animals paths.8
Associated species
Roemer’s fescue (Festuca idahoensis var. roemeri), Danthonia (Danthonia californica), and red fescue (Festuca rubra). Native graminoids include field woodrush (Luzula campestris) and praire junegrass (Koeleria macrantha). Forbs include field chickweed (Cerastium arvense), woolly sunflower (Eriophyllum lanatum) and Hooker’s onion (Allium acuminatum)6. Also found growing along with Phacelia sp., Sedum sp. and various mosses[11].
Collected as
Seed, or division after flowering[12]
Collection restrictions or guidelines
Allow pods to dry on plant; break open to collect seeds.[13] Properly clean.
Seed germination
Seeds germinate in 2 - 3 weeks at 21°c.13
Seed life
Seeds can be successfully stored12. However, seeds are very small and likely decrease in viability in a short amount of time. It is best to surface sow the seed as soon as it is ripe13.
Recommended seed storage conditions
Properly cleaned, store at cool temperature with low moisture.
Propagation recommendations
Sow the seed as soon as it is ripe in a light position in a cold frame. Seed can also be sown in spring. When large enough to handle, prick the seedlings out into individual pots and plant them out in the summer.13
Conduct divisions after flowering, usually in the spring. The divisions can be planted into their permanent plots if required.13
Soil or medium requirements
It is recommended that hairy rockcress is planted in light (sandy), medium (loamy) and heavy (clay) soils and requires well-drained soil. The plant can grow in acid, neutral and basic (alkaline) soils.
Recommended planting density
15-18 in (38-45 cm)12
Care requirements after installation
Water once, after installation.
Normal rate of growth or spread
Rate of spread can vary depending on environmental conditions.
Stems, which often are purplish below, usually are single, but occasionally two or three arise from a tough, persistent base, growing to 0.6m.1 Hairy rockcress is hardy and is not frost tender. It flowers from May to July. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees, Lepidoptera (Moths & Butterflies) and insects.11
Data compiled by: Amy Lambert, 04/06/03