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A deciduous shrub up to 6 ft or more high in the wild, rarely seen more than half as high in this country; young shoots thick and stout, woolly. Leaves broadly oval or broadly ovate, sometimes roundish in general outline, but five- or seven-lobed, after the fashion of the large-leaved American red oaks like Quercus rubra; minutely toothed, 3 to 8 in. long, two-thirds to fully as wide, dark dull green and glabrous above, downy beneath; stalk 1 to 21⁄2 in. long. Panicle erect, 4 to 10 in. high, round-topped, pyramidal. Outer flowers sterile, 1 to 11⁄2 in. diameter, white, changing with age to a purplish shade. Fertile flowers very numerous, crowded, 1⁄8 in. diameter; petals five, oblong. Flower-stalks furnished with loose hairs. Blossoms from June to September. Bot. Mag., t. 975.
Native of the south-eastern United States; introduced in 1803. From all the cultivated hydrangeas this is readily distinguished by its large scalloped leaves. It is very handsome both in foliage and flower, but has the reputation of being slightly tender. Young plants may be so, but become hardy once a woody framework has been built up. This hydrangea needs a moist, fairly rich soil and should be given a sheltered and not too shaded position. Indeed, provided it is kept well mulched with leaf-mould it might thrive best in full sun; unless the wood is well ripened, the terminal buds may be lost during the winter, and no flower will then be produced. In favourable seasons the leaves turn crimson, orange, or purple in the autumn. Propagation is by layers, suckers, or cuttings taken soon after midsummer and rooted in bottom-heat.
In previous editions it was stated that a broader-leaved and superior form was sometimes distinguished as “H. platanifolia”. Such plants are not now in commerce in Britain, so far as is known – at least not under that name, the origin of which cannot be traced. It is interesting, however, to note that a plant in the Berlin Botanic Garden, figured in Krussmann’s Handbuch der Laubgeholze (Vol. 2, pl. 3), bears some leaves that are distinctly plane-like.