Hydrangea serrata

Mountain Hydrangea
H. serrata
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Cornales
Family:	Hydrangeaceae
Genus:	Hydrangea
Species:	H. serrata
Binomial name
Hydrangea serrata (Thunb.) Ser.
Synonyms
H. macrophylla serrata

Hydrangea serrata is a species of Hydrangea native to mountainous regions of eastern Asia and Japan; common names include mountain hydrangea and tea of heaven. It is widely cultivated as an attractive ornamental shrub throughout the world in areas with suitable climate and soil.

Taxonomy

Considerable difficulties exist in the nomenclature for mountain hydrangea and closely associated hydrangeas. It is treated here as an individual species in accordance with van Gelderen and van Gelderen.^[1] Many botanists, however, view mountain hydrangea as no more than a subspecies of bigleaf hydrangea (H. macrophylla).^[2] There are many cultivars available for mountain hydrangea.

Natural range

Eastern Asia and Japan in woodlands of mountainous regions to 5,000 feet. It is planted world wide in suitable climates and soils as an attractive ornamental.

Characteristics

Mountain hydrangea is similar to big leaf hydrangea except it is a smaller more compact shrub with smaller flowers and leaves; it is also more hardy than bigleaf hydrangea. Mountain hydrangea is a deciduous shrub with a rounded habit that typically grows 2 to 4 feet tall. It features dark green, serrated (toothed), ovate leaves (to 6" long), and clusters of long-blooming summer flowers. Both showy sterile florets and less showy fertile florets appear in each cluster. It flowers from July to August, with blue or pink lacy flowerheads. The flowers are perfect, having both male and female parts; they are insect pollinated.

A closeup of several flowers.

Propagation

Seeds can be surface sown in a greenhouse in spring. When large enough, seedlings may be outplanted into individual pots.

Softwood cuttings can be rooted during summer, as can hardwood cuttings during fall and winter. Mound layering can be accomplished in the spring.

Cultivation

Mountain hydrangea is best grown in rich, medium moisture, well-drained soils in partial shade. It tolerates full sun only if grown with consistently moist soils. Soil pH affects the flower color of mountain hydrangea in the same manner as it does with bigleaf hydrangea—namely, bluish in highly acidic soils and lilac to pink in slightly acidic to alkaline soils. The flowers occur on old wood, and little pruning is needed. It may be pruned after flowering by cutting back flowering stems to a pair of healthy buds. Weak or winter-damaged stems can be pruned in early spring.

Mountain hydrangea are winter hardy to USDA Zone 6, and it can be grown in USDA Zone 5 with protection (e.g., mulch and burlap wrap). It may lose significant numbers of flower buds or die to the ground in harsh winters, impairing or decimating the bloom for the coming year. Plants are hardy to about -13 degrees Fahrenheit when dormant, but the young growth in spring can be killed by late frosts.

Problems

Some susceptibility occurs to honey fungus, bud blight, bacterial wilt, leaf spot, and powdery mildew. Aphids are occasional summer pests.

Uses

Mountain hydrangea makes a good specimen or accent plant for protected locations near homes or patios. It can be grown as a low hedge, and it is quite wind tolerant.

The leaves of mountain hydrangea contain pyllodulcin, a natural sweetener, and are used to make regionally popular herbal teas^[1] (sugukcha in Korea and amacha in Japan). Amacha tea is used in Japan in the celebration Buddha's birth.

Chemistry

Phyllodulcin is an isocoumarin found in H. serrata.^[3]

References

1. ^ ^{a b} C.J. van Gelderen; D.M. van Gelderen. 2004. Encyclopedia of Hydrangeas. Timber Press. 280 p.
2. ^ Sandra Reed; Timothy Rinehart. Hydrangea Macrophylla and Serrata - Should We Lump 'em Or Split 'em?
3. ^ Accumulation of phyllodulcin in sweet-leaf plants of Hydrangea serrata and its neutrality in the defence against a specialist leafmining herbivore. Mami Ujihara, Masateru Shinozaki and Makoto Kato, Researches on population ecology, Volume 37, Number 2, pp. 249-257, doi:10.1007/BF02515827

External links

• USDA ARS Germplasm Resources Information Network: Hydrangea macrophylla serrata.
• Plant Guide: Hydrangea serrata (Mountain Hydrangea)
• Plants for a Future: Hydrangea serrata.
• Missouri Botanical Garden: Hydrangea serrata