Populus tremula

Several ieatures mark out this native poplar from all other kinds, its leaves are oval or almost round, with a curiously wavy edge (see Figures 62 and 66). They have very slender long stalks that are flattened sideways, and this allows them to tremble or quiver in the slightest breeze. The winter twigs are only slightly angular and the buds have a plump oval outline. Both male and female catkins look remarkably hairy - rather like hairy caterpillars - by reason of their very deeply divided hair-tufted bracts. These are purplish in colour - an unusual hue in the late February scene; on the male tree it contrasts with the plentiful yellow pollen shed by the stamens. The fruiting catkins, which ripen in May, also look very fuzzy, due in this case to numerous white hairs on each little seed.

Cuttings of aspen are hard to strike, so this tree is raised from either sucker shoots detached from the parent tree, or else by seed. The germination of the minute seed, which is only viable for a few days after ripening, is shown in Figure 65; it is remarkably quick, taking only 6 days.

Aspen seldom forms a tall tree; it is most often seen as a thicket of sucker shoots in some marshy spot on a clay soil.

Its natural range includes the whole of the British Isles and it is a very hardy tree. Its wood is the best of all timber for matchmaking, and it is so used in Scandinavia. Poland and Russia. But in Britain it never reaches an acceptable size, so it is not planted for timber here.

The name of 'aspen' comes from an Old Teutonic word for a poplar tree, represented by Espe in German and osp in Norwegian, In Gaelic it is called eubh or more poetically cran crithea-nach, 'the shaking tree' because of the incessant motion of its leaves. The Welsh name is sethnen, but it is also called, again because its leaves are never still, coed tafod merched or 'the tree of the woman's tongue.'

FIGURE 62

Leaves and fruiting catkins of aspen in May (life size). The single seed-pod left, is splitting to release the small seeds, each tulted with hairs (X 7).

FIGURE 63

Winter twig of aspen (xf) with a single stoutly oval bud (x4).

FIGURE 64

Aspen catkins in late February.

Above: female catkins (Xj) with a single flower (X8) showing a dark purple hairy bract, green cup, and conical ovary topped by two bi-lobed stigmas.

Below: male catkins (X;) and a single flower (XS). The dark purple, hairy bracts enlarge as the male catkins age. The stamens are dark purple when young, but appear yellow with pollen later.

figure 65 (rlgbrt

The germination of an aspen seed on damp earth in May. Left swelling 18 hours after sowing; centre, forming a root and a shoot 3 days after sowing. Right extending root and opening two seed-leaves, only 6 days after sowing (X10), figure 65 (rlgbrt

The germination of an aspen seed on damp earth in May. Left swelling 18 hours after sowing; centre, forming a root and a shoot 3 days after sowing. Right extending root and opening two seed-leaves, only 6 days after sowing (X10),

Green Vegetable Leaf

FIGURE 6i

Poplar leaves and leaf-stalks; note random veining of leaves. (All half natural size.)

Top left-Black Italian poplar, fbpu/us'Serotina'triangular-ovate.

Top centre;"Native Black poplar, P. nigra, a diamond.

Top right Grey poplar. P. canescens. a slightly lobed leaf - shape is variable.

Bottom left White poplar, P. alba, distinctly lobed leaf - shape is variable.

Bottom right Aspen, P. tremula, round, with typically narrow leaf-stalk, associated with fluttering foliage.

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