Alula

The alula, or bastard wing, (plural alulae) is a small projection on the anterior edge of the wing of modern birds and a few non avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ala, meaning "wing". The alula is the freely moving first digit, a bird's "thumb," and typically bears three to five small flight feathers, with the exact number depending on the species. There also are minor covert feathers overlying the flight feathers. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge.

Function

In most situations, the alula is held flush against the wing; however, it can be manipulated. When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall. The tip of the alula forms a tiny vortex that forces the airflow over the wing to better bind to it. During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed.

Alula (disambiguation)

The alula is a part of a bird's wing.

Alula may also refer to:

Brighamia insignis

Brighamia insignis, commonly known as Ōlulu or Alula in Hawaiian, or colloquially as the vulcan palm or cabbage on a stick, is a critically endangered species of Hawaiian lobelioid in the bellflower family, Campanulaceae. It is native to the islands of Kauaʻi and Niʻihau. This short-lived perennial species is a member of a unique endemic Hawaiian genus with only one other species. It is now extremely rare. In 1994 the United States Fish and Wildlife Service reported five populations totaling 45 to 65 individuals, and listed the plant as an endangered species.

B. insignis is a potentially branched plant with a succulent stem that is bulbous at the bottom and tapers toward the top, ending in a compact rosette of fleshy leaves. The stem is usually 1–2 m (3.3–6.6 ft) in height, but can reach 5 m (16 ft). The plant blooms in September through November. It has clusters of fragrant yellow flowers in groups of three to eight in the leaf axils. The scent has been compared to honeysuckle.Petals are fused into a tube 7 to 14 cm (2.8 to 5.5 in) long. The fruit is a capsule 13 to 19 mm (0.51 to 0.75 in) long containing numerous seeds.