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Gyrocarpus americanus is a slender, deciduous tree with smooth, grey bark. The tree grows to about 12 m in height. The leaves are spirally arranged, crowded near the ends of the branches, and grow up to 150 × 120 mm in size. They are ovate, often 3-lobed, dark green above, paler and greyer below, with velvety surfaces, 3-veined from the base ...
Male flowers Seeds of Fraxinus excelsior, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara. It is a large deciduous tree growing to 12–18 m (39–59 ft) (exceptionally to 43 m or 141 ft) tall with a trunk up to 2 m (6.6 ft) (exceptionally to 3.5 m or 11 ft) diameter, with a tall, narrow crown. [2]
The seeds, popularly known as "keys" or "helicopter seeds", are a type of fruit known as a samara. Some Fraxinus species are dioecious, having male and female flowers on separate plants but sex in ash is expressed as a continuum between male and female individuals, dominated by unisexual trees.
The shape of a samara enables the wind to carry the seed further away from the tree than regular seeds would go, [3] and is thus a form of anemochory. In some cases the seed is in the centre of the wing, as in the elms (genus Ulmus), the hoptree (Ptelea trifoliata), and the bushwillows (genus Combretum).
The distinctive fruits are called samaras, "maple keys", "helicopters", "whirlybirds" or "polynoses". These seeds occur in distinctive pairs each containing one seed enclosed in a "nutlet" attached to a flattened wing of fibrous, papery tissue. They are shaped to spin as they fall and to carry the seeds a considerable distance on the wind.
The sandbox tree's fruits are large, pumpkin-shaped capsules, 3–5 cm (1–2 in) long, 5–8 cm (2–3 in) diameter, with 16 carpels arranged radially. Its seeds are flattened and about 2 cm (3 ⁄ 4 in) diameter. The capsules explode when ripe, splitting into segments and launching seeds at 70 m/s (250 km/h; 160 mph). [5]
The fruits are paired winged seeds or samaras, ... The tree now has a girth of 5.9 metres (19 feet, 4 inches) [74] and a 2005 study dated the tree to 1680. [75]
The fruit matures in about 6 months, to 2–3 centimetres (0.8–1.2 in) diameter, and comprises a dense spherical cluster of achenes with numerous stiff hairs which aid wind dispersal; the cluster breaks up slowly over the winter to release the numerous 2–3 mm (0.08–0.12 in) seeds. The London Plane is one of the most efficient trees in ...