Questões de Concurso

Round-leaved sundew has, as the name suggests, round leaves up to 1 cm across. The leaf stalks are covered in tiny hairs. It is often found growing on hummocks of sphagnum moss and on wet heaths. In late summer, both species of sundew produce tiny flowers, borne on long stems which arise from the centre of the rosette of leaves.

Sundews are carnivorous plants which grow in nutrient-poor, acidic soils. They supplement their nutrient supply by catching and digesting small invertebrates. The leaves are covered with red hairs, each tipped by a droplet. The name "sundew" refers to these glistening droplets resembling dew. The hairs are tiny glands, producing a sticky sweet-smelling secretion which attracts small insects like flies. Each droplet is a deadly trap, ensnaring the unsuspecting insect.

As the fly struggles to escape, the mucilage starts to clog up its spiracles, tiny holes through which it breathes. The leaf hairs are very sensitive, having detected the insect, they start to curl inward. Very slowly the leaves also curl inwards and the droplets exude an enzyme which starts to digest the soft parts of the fly. The resulting fly soup is then absorbed by the leaves. Several days later, the leaves uncurl and the remains of the insect are discarded. The droplets then reappear at the end of the tentacles and the trap is reset. It is estimated that a sundew can catch up to 2,000 insects during the summer.

Sundew flowers only open in sunny weather for a few hours during the day. Raised high above the insect-trapping leaves, the flowers attract pollinators such as flies and midges. However, the flowers can also self-pollinate. In winter, the sundews which grow in temperate climates form a resting bud to survive the cold, from which they re-grow in spring.

Ross-shire through the Lens: Lochcarron Highland Games Attadale wonderland!Ross-shire through the Lens: Lochcarron Highland Games Attadale wonderland!

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Also growing in nitrogen-poor bogs and wet acidic heaths is another carnivorous plant, common butterwort. In spring, small green stars of yellow-green basal leaves appear flat to the ground. From this rosette two or three upright stalks grow, each producing small deep-purple flowers. Bees mainly pollinate these flowers but they can also self-pollinate.

Common butterwort also tops up its nutrients by catching and digesting prey. However, its bee pollinators are too large to be caught. Nearer the ground, small insects are trapped on the starfish-like leaves. These are covered in tiny sticky drops of mucilage so that they always look wet. The insects are attracted to the moisture and land on the leaf but quickly become stuck. The leaf edges slowly curl inwards to prevent escape and the plant secretes digestive enzymes which break down the soft parts of the insect. The liquefied nutrients are absorbed by the leaf before the leaf eventually uncurls to reveal the chitinous husk.

The common name, 'butterwort', refers to the fatty appearance of the leaves. Wort is an Old English word for a plant or herb. It was believed that rubbing butterwort leaves on a cow's udders would protect the cow from evil spirits and ensure a good supply of butter. The leaves were also used to curdle and thicken milk during cheese and butter making.

Birds of note this week included the queen eider in Lerwick harbour, a black-throated diver at Urafirth, an osprey in Unst, an eclipse male ring-necked duck at Clickimin, a ring-billed gull on Noss and a long-tailed skua at the airstrip in Foula.

The long-tailed skua is a scarce migrant, more commonly observed offshore in spring and autumn. Long-tailed skuas have a circumpolar distribution, breeding on the Arctic tundra, and are found in northern parts of Scandinavia. In summer, lemmings are a major part of their diet. After the breeding season, they migrate to the south Atlantic, spending the winter months at sea, feeding on fish. The smallest of the skuas, the long-tailed skua is about the size of a black-headed gull. Slim with long, slender wings, the flight is graceful and tern-like. In adult summer breeding plumage, it is readily identified by very long central tail feathers which can measure up to 20cm. The dark brown-grey upperparts, with black patches on the wings, contrast with pale underparts and a dark cap.

Cetacean sightings this week have included Risso's dolphin, white-beaked dolphin, common dolphin, harbour porpoise, minke and orca.