Frosted Orache

Frosted orache is a monoecious annual herb that grows to about 30 cm tall with decumbent to ascending stems that sprawl across sandy or sand and shingle beaches. It has a short taproot and many fibrous side-roots that also spread widely. The stems are generally red, densely covered with white, mealy hairs, and frequently branched. The leaves are alternate. The lower ones are broadly rhombic in outline, about 4 cm long, with a cuneate base, at least 2 large lobes, and often several broad teeth around the margin. The upper leaves become progressively narrower until the ones within the inflorescence are almost linear. All the leaves have only a short petiole, about 0.5 cm long. The leaves are silvery-grey in colour and scaly or mealy, especially below. Flowering occurs in late summer. The inflorescence is a panicle of short spikes of dense silvery-white glomerules, or clusters of 2–4 tiny, petal-less flowers. Flowers are of two types. The male ones are about 1 mm across, with 4 or 5 tiny tepals and 4 or 5 stamens. The females consist of an ovary with a short style and two stigmas, situated between two bracteoles that enlarge at maturity to about 10 mm long. …

Frosted orache is quite a rare plant, globally, being largely restricted to the Atlantic coasts of western Europe - mainly around Britain and Ireland, from northern Spain to Denmark and Sweden. In Norway it is mainly on some southern beaches, and there are small outlying populations on the Mediterranean coasts of Spain, France and Corsica. It is scattered or common around the entire coastline of Britain and Ireland, including Shetland and Orkney, and the Channel Isles, and has seemingly been increasing in recent decades, especially around Ireland. Despite this, it is generally described as occurring in small, often transient populations. There is no evidence of it spreading successfully onto salt-treated roadsides, although many other coastal species do so. There has been much confusion about its occurrence in North America owing to its similarity to Atriplex canescens. Early sightings from Virginia were errors of identification, although Linnaeus himself listed it as an American plant, in Species Plantarum. Some sources still list it as an introduction over quite a wide area from New York state to Newfoundland, while others report that it is at best very rare. …

The habitat of this species is on sandy beaches, between the mean spring high tide line and the equinoctial high tide line. Each year this strandline vegetation, which is classified as habitat 1210 in the EUNIS habitat classification system, is destroyed by exceptional tides with a coefficient of 100–120. In Britain, this is the SD2 Honkenya peploides-Cakile maritima strandline community, or sometimes (on sand and shingle beaches) SD1 Rumex crispus-Glaucium flavum vegetation. Frosted orache is therefore adapted to complete its life cycle during the summer months and to tolerate salty water at a shallow depth. Some accounts used to suggest that the fertility of beaches like these is particularly high, due to rotting seaweed mixed into the sand, but more recent studies show that while this might be true in some circumstances, a sandy beach is usually very nutrient poor. Frosted orache is primarily wind-pollinated but can be self-pollinating. In Britain there are only two (possibly three) species of insect known to produce galls on frosted orache. …