About Arabidopsis lyrata (L.) O'Kane & Al-Shehbaz
Arabidopsis lyrata (L.) O'Kane & Al-Shehbaz is a diploid perennial plant, reaching 10–40 centimetres (4–16 in) in height. It has highly distinct basal leaves, and small pure white flowers. Stem leaves are arranged alternately, with linear, slightly curved smooth margins and tapered bases. The species’ leaves produce glucosinolates and have trichomes, which act as defense mechanisms against insect herbivores and other potential threats such as fires and human activity. Individual flowers are very small, measuring 3–8 mm across. They have four lobes, and grow on widely ascending pedicels that are 7 to 12 mm long. This species is insect pollinated, and blooms from May through June, with fruits developing in early August. Fruits are elongated, papery, and 2–4.5 millimetres (0.08–0.18 in) long. Seeds are 1 mm (0.04 in) long and arranged in a single row. Arabidopsis lyrata occurs mostly in subarctic or subalpine areas with thin soils, including rock faces, eskers, talus slopes, and exposed coastal zones. Individual plants can grow as solitary rosettes, and reproduce asexually through clonal patches. This species cannot survive in agro-ecosystems with abundant weeds, and grows best under low competition. Its life cycle relies on completing germination, growth, and seed set in a very short window before other plant species block access to light. It has a circumpolar distribution, found across northern and central Europe, Asia, and North America. In the U.S. state of Virginia, it grows in rocky woodlands, barrens, and crevices or thin-soiled ledges on outcrops of limestone, dolomite, siltstone, metasiltstone, amphibolite, metabasalt, diabase, and other mafic and felsic igneous and metamorphic rocks. It also occurs in eastern United States, where it is usually restricted to sand bars. In Europe, it is found in southern Germany and restricted areas of Sweden. For North American populations of Arabidopsis lyrata ssp. lyrata, outcrossing is typical in the center of the species’ range, while populations at range margins shift toward selfing.
