''Hydrangea radiata'' is an attractive, deciduous shrub up to 3 m tall in the

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

family

Hydrangeaceae Hydrangeaceae is a family of flowering plants in the order Cornales, with a wide distribution in Asia and North America, and locally in southeastern Europe. Description The genera are characterised by leaves in opposite pairs (rarely whorled or ...

. Its natural range is limited to the southern

Appalachians The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

, where it is fairly common.Lance, Ron. 2004 Woody Plants of the southeastern United States: A winter guide. The University of Georgia Press. 456 p. Its common names—silverleaf hydrangea or snowy hydrangea—reflect its distinctive foliage which is dark green on top and silvery white below;''Hydrangea radiata''
The Arnold Arboretum of Harvard University. Bulletin of Popular Information. 1922. the sharply contrasting foliar colors makes this shrub conspicuous at a distance, especially in a breeze.Dirr, Michael A. hydrangeas for American gardens. Timber Press. 240 p.

Range/Habitat

Silver hydrangea is native to the mountainous region (usually above 2,000 feet elevation) represented by the southern

Blue Ridge Mountains The Blue Ridge Mountains are a physiographic province of the larger Appalachian Mountains range. The mountain range is located in the Eastern United States, and extends 550 miles southwest from southern Pennsylvania through Maryland, West Virgin ...

from southeast

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

, east to

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

and northwestern

South Carolina )''Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no) , anthem = " Carolina";" South Carolina On My Mind" , Former = Province of South Carolina , seat = Columbia , LargestCity = Charleston , LargestMetro = ...

, and south to northeastern

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

. It typically occurs near streams, rocky outcrops, and along roads, especially in the headwaters of the

Chattooga River The Chattooga River (also spelled Chatooga, Chatuga, and Chautaga, variant name Guinekelokee River) is the main tributary of the Tugaloo River. Water course The headwaters of the Chattooga River are located southwest of Cashiers, North Carolin ...

and also in the

French Broad River The French Broad River is a river in the U.S. states of North Carolina and Tennessee. It flows from near the town of Rosman in Transylvania County, North Carolina, into Tennessee, where its confluence with the Holston River at Knoxville forms ...

Valley. It is conspicuous along roadsides near the junction of North Carolina, South Carolina, and Georgia—in the vicinity of

Highlands Highland is a broad term for areas of higher elevation, such as a mountain range or mountainous plateau. Highland, Highlands, or The Highlands, may also refer to: Places Albania * Dukagjin Highlands Armenia * Armenian Highlands Australia *Sou ...

Cashiers Cashiers is a census-designated place (CDP) and unincorporated village located in southern Jackson County, North Carolina, United States. As of the 2020 United States census, the community had a total population of 657, up from 157 at the 2010 c ...

, and

Rosman, North Carolina Rosman is a town in Transylvania County, North Carolina, United States. The population was 576 at the 2010 census. The northern terminus of U.S. Route 178 is less than one mile northwest of Rosman on U.S. Route 64. The Pisgah Astronomical Research ...

. Some outlier occurrences of silverleaf hydrangea have been locally observed in the

Piedmont Region it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...

; these populations may have escaped from cultivation.

Taxonomy

Silverleaf hydrangea is similar to the more widespread smooth hydrangea (''

Hydrangea arborescens ''Hydrangea arborescens'', commonly known as smooth hydrangea, wild hydrangea, sevenbark, or in some cases, sheep flower, is a species of flowering plant in the family Hydrangeaceae. It is a small- to medium-sized, multi-stemmed, deciduous shru ...

'') and ashy hydrangea (''

Hydrangea cinerea ''Hydrangea cinerea'', the ashy hydrangea or gray hydrangea, is a small to medium sized, deciduous shrub up to 3 m tall; its natural range is interior regions of the southeastern United States.Lance, Ron. 2004 Woody Plants of the southeastern Uni ...

''). At one time both silverleaf hydrangea and ashy hydrangea were considered subspecies of smooth hydrangea.McClintock, E. 1957. A monograph of the genus ''Hydrangea''. Proceedings of the California Academy of Sciences 29: 147-256. However, most taxonomists now consider them to be separate species, and that usage is adopted here.Pilatowski, Ronald E. A taxonomic study of the ''Hydrangea arborescens'' complex. Castanea 47: 84-98. Evidence for separating these three closely related, native hydrangeas is based largely on cross-pollination experiments conducted by Ronald Pilatowski. The crosses yielded few viable seeds at best, indicating that despite overlapping ranges and characteristics, the plants maintained their genetic purity and their unique

phenotypic In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

characteristics.

Characteristics

Saxifragaceae - Hydrangea arborescens subs

The inflorescence of silver hydrangea is a

corymb Corymb is a botanical term for an inflorescence with the flowers growing in such a fashion that the outermost are borne on longer pedicels than the inner, bringing all flowers up to a common level. A corymb has a flattish top with a superficial re ...

. The showy, sterile flowers (white to near white) and are comparatively abundant (2-15 per bloom) and are borne around the periphery of the corymb; they are usually greater than 1 cm in diameter. The leaves of silverleaf hydrangea are large (8 to 15 cm long), opposite,

serrated Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pr ...

ovate Ovate may refer to: *Ovate (egg-shaped) leaves, tepals, or other botanical parts *Ovate, a type of prehistoric stone hand axe *Ovates, one of three ranks of membership in the Welsh Gorsedd *Vates In modern English, the nouns vates () and ovat ...

, and

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

. The upper leaf surface has

hairs Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...

along the veins. The lower leaf surface is densely covered with felt-like hairs, appearing bright white or silver; when viewed under magnification, these hairs are without

tubercles In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection ...

(ashy hydrangea has numerous tubercles). These hairs are so thick that the lower surface of the leaf 's

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...

cannot be seen.

Uses

This attractive shrub has considerable landscaping potential in areas with a suitable climate and soils. Requiring cool, moist habitats in the shade, silverleaf hydrangea is not as tolerant of the heat and drought as smooth hydrangea. It is also more difficult to root from cuttings than either smooth or ashy hydrangeas. Silverleaf hydrangea produces more showy flowers than smooth hydrangea or ashy hydrangea. Silverleaf hydrangea is suitable for

hardiness zone A hardiness zone is a geographic area defined as having a certain average annual minimum temperature, a factor relevant to the survival of many plants. In some systems other statistics are included in the calculations. The original and most wide ...

s 4 to 9, although highly protected locations would be advisable in areas warmer than zone 6. Several popular cultivars are available (Samantha and Terri Greer).

References

External links

Cook, Will. Trees, shrubs, and woody vines of North Carolina. Silverleaf Hydrangea (''Hydrangea radiata'').The Arnold Arboretum of Harvard University. Bulletin of Popular Information. 1922. ''Hydrangea radiata''.
{{Taxonbar, from=Q164376

radiata Radiata or Radiates is a historical taxonomic rank that was used to classify animals with radially symmetric body plans. The term Radiata is no longer accepted, as it united several different groupings of animals that do not form a monophyletic ...

Flora of the Southeastern United States Flora without expected TNC conservation status