''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 (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

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, are a mountain range in eastern to northeastern North America. The term "Appalachian" refers to several different regions associated with the mountain range, and its surrounding terrain ...

, 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 and 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 regions of the United States, physiographic province of the larger Appalachian Highlands range. The mountain range is located in the Eastern United States and extends 550 miles southwest from southern ...

from southeast

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

, east to

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

and northwestern

South Carolina South Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders North Carolina to the north and northeast, the Atlantic Ocean to the southeast, and Georgia (U.S. state), Georg ...

, and south to northeastern

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

. 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 Car ...

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, North Carolina, Rosman in Transylvania County, North Carolina, into Tennessee, where its confluence with the Holston R ...

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 Africa * Highlands, Johannesburg, South Africa * Highlands, Harare, Zimbab ...

, Cashiers, 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 Resea ...

. Some outlier occurrences of silverleaf hydrangea have been locally observed in the Piedmont Region; 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 or sevenbark, is a species of flowering plant in the family Hydrangeaceae. It is a small- to medium-sized, multi-stemmed, deciduous shrub up to tall that is native to the eastern Uni ...

'') and ashy hydrangea ('' Hydrangea cinerea''). 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 (physical form and structure), its developmental processes, its biochemical and physiological propert ...

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 In lexical semantics, opposites are words lying in an inherently incompatible binary relationship. For example, something that is ''even'' entails that it is not ''odd''. It is referred to as a 'binary' relationship because there are two members i ...

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 or ovate, a term for ancient Celtic bards ...

, 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 Leaf, 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 fin ...

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, b ...

(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 Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

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 widely ...

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 Symmetry (biology)#Radial symmetry, radially symmetric body plans. The term Radiata is no longer accepted, as it united several different groupings of anim ...

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