Page:TheTreesOfGreatBritainAndIreland vol01.djvu/93



A lofty tree, attaining in America in the most favourable conditions a height of 190 feet, and a stem diameter of 10 feet. Bark grey and smooth in young trees, becoming darker in colour and furrowed in old trees. Roots, fleshy with pale brown bark, having an aromatic odour and pungent taste.

Leaves extremely variable in shape, but generally saddle-shaped or lyrate in outline, with a rounded or cordate base, and a truncate emarginate apex, the midrib being prolonged into a short bristle. Sometimes they are quite entire, but are more usually lobed, the lobes varying from 2-6 or even 8 in number, and often ending in a point. Venation pinnate. The leaves are 3-5 inches in length and in breadth, dark green and smooth above, lighter in colour and minutely pubescent underneath. Stalks about as long as the blades, angled and slender, so that the leaves quiver with any movement of the air. In autumn they turn bright yellow in colour, and give the tree a handsome appearance.

Two lateral stipules occur on the twigs, attached a little higher up than the insertion of the leaf-stalk. These are the scales which have formed the buds of the previous winter; and, as a rule, they shrivel up and fall off when the young leaves are fully matured; but some of them remain on vigorous shoots till late in summer.

The flowers resemble a tulip in shape, being 1½–2 inches long, with a width of 2 inches at the summit. The petals are greenish white, with an orange-coloured band at the base, which secretes nectar attractive to bees. These visit the trees in myriads in May, the flowering season in Illinois.

The fruit, light brown in colour, is a cone made up of a large number (about 70) of ripe carpels, which consist of a 4-ribbed pericarp surmounted by a flattened woody wing (the enlarged style). The wing may carry the seed by currents of air 300 or 400 feet from the parent tree. The carpels remain on the tree till thoroughly dry, some usually persisting throughout the winter on the receptacle, a few falling at a time as the wind dislodges them. The outer ones are nearly always sterile. The carpels will float in water for nearly a year without sinking; and this may explain the distribution of the tree along the banks of rivers. The seed has a fleshy albumen, in the summit of which is situated a minute embryo.

Seedling.—The seedling has two aerial short-stalked oval cotyledons about

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