View source for Hydrangea macrophylla subsp. macrophylla

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Hydrangea opuloides, Koch (H. hortensis, Smith. H. hortensia, DC. H.japonica, Sieb.). Shrub, to 8 ft., almost glabrous: lvs. ovate or ovate-elliptic, acuminate or acute, coarsely serrate, 5-8 in. long: fls. in large cymes without bracts, white, bluish or pink, few or all of them sterile.—The greenhouse hydrangea. June, July, but blooming in winter under glass. A large number of varieties have been intro. from Japan and China, where this species has been extensively cult, for many centuries, and where it is native. The following are some of the beat known. They may be divided into 3 groups:

(1) Japonica group: cymes flat, with sterile and fertile fls.
(2) Hortensia group: cymes globose, with almost all fls. sterile.
(3) Stellata group: fls. with many narrow sepals.

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