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Deciduous Flowering Shrubs - Part 4

© Marge Talt

Hydrangeas - Part 1

Hydrangeas are some of the most sumptuous summer-flowering shrubs for our shady gardens. These faithful summer bloomers are regaining the popularity they somehow lost for a time. And rightfully so. Some regard the mopheads as blatant and blowzy. I find them bountiful and lovely, but if you're one who is not fond of them, the lace caps should suit your taste. The genus offers a size for every garden, from small dwarfs to tall tree forms. Flowering starts in early summer and the heads remain decorative right up until mid-winter.

Hydrangeas belong to the hydrangea family, Hydrangeaceae, which also contains shrubs like Deutzia, the woody vine, Schizophragma, and herbaceous perennials like Kirengeshoma. I have also seen it listed as belonging to the family Saxifragaceae, but think this is now incorrect. The genus Hydrangea consists of mostly deciduous hardy and tender shrubs and woody climbers. A few of the tender species are evergreen. They are endemic to the Himalayas, North and South America, and central and eastern Asia, primarily China, Japan and Korea.

As ubiquitous as hydrangeas are, there is considerable confusion over their names. The taxonomist lumpers and splitters are merrily at work, combining and splitting various species and controversy abounds. Research turns up references to species, such as Hydrangea serrata, which is considered a subspecies of H. macrophylla by sources such as GRIN. In an effort to sort them out for both of us, I have adopted the GRIN listing, which seems most current to me, with additions from the RHS Plant Finder and selected nurseries who have been collecting what are likely new and certainly unusual species in Japan, China and Korea.

Flower Form and Color

Flower Form

Hydrangea flowers are composed of small, perfect fertile flowers and large sterile, male flowers. The mopheads, or big leaf or hortensia forms, as well as those of H. arborescens have globes of sterile flowers that may or may not conceal the smaller fertile ones.

The lace cap forms have fewer sterile flowers surrounding a central mass of fertile ones. Those with flowers arranged in conical panicles include the H. quercifolia (oakleaf hydrangea) and the panicle hydrangea, H. paniculata. Depending on the species or cultivar, these may consist of a few large sterile flowers with many fertile ones, or the fertile flowers may be absent or covered by the sterile flowers.

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