Taxonomical History and Botanical Descriptions of Hydrangea species

Taxonomical History and Botanical Descriptions of Hydrangea species

For any keen gardener wanting to know even more about their hydrangeas we have included the following taxonomical history and botanical descriptions of hydrangea species we have grown and are featured on this website.


Carl Linnaeus: Species Plantarum, 1753. (from the Latin Hydr, water, and the Greek angeion, vessel; alluding to the cup-shaped seed capsule. Or, from the ancient Greek hydor, water, and aggos, jar). Named by botanist Carl von Linnaeus (1707-1778), published in Species Plantarum in 1753.

FAMILY: Hydrangeaceae. A genus of about 50 species (see of entomophilous shrubs, sometimes tree-like, erect, ascending, spreading or climbing, natives of N. and S. America and East Asia. Branchlets, leaves, and inflorescences variously hairy. Flowers fertile or sterile.

LEAVES: in opposite pairs or ternate, deciduous or evergreen. Leaves are exstipulate, simple, entire, serrate or pinnately lobed, ovate or obovate, acuminate, cuneate. Petiole present. The upper leaf surface is glossy, smooth, matt, hairy, according to the species; the lower dull with a conspicuous network of pinnate veins.

INFLORESCENCE: terminal, a corymbose cyme, umbellate cyme, panicle or thyrse; occasionally axillary, bracts deciduous . Peduncle present. Fertile flowers usually very numerous, bisexual, small; pedicel short. Calyx tube adnate to ovary, 4- or 5-dentate, persistent. Corolla lobes 4 or 5, free, rarely connate and forming a calyptra, ovate or spatulate, valvate. Stamens usually 8 or 10 (but up to 25), inserted on disc; filaments linear; anthers oblong to subglobose, apex subrounded to obtuse. Ovary inferior to 2/3 superior, imperfectly or perfectly 2-4(or 5)-loculed; placentation parietal or axile; ovules numerous. Styles 2-4(or 5), free or basally connate, persistent; stigmas terminal or decurrent along style adaxially. Sterile flowers few (more numerous in cultivated varieties), sometimes absent, borne at margin of inflorescence, with no stamens or pistils but with sepals 2 to 5, entire, serrated, elliptical, oval, rounded, petaloid, and enlarged. Under cultivation, and sometimes in a wild state, the corymbs may consist entirely of sterile flowers and are then very showy. Whilst the majority have white sterile flowers, some cultivars of H. macrophylla and H. macrophylla ssp. serrata are pink and several have a tendency to blue.

SEEDS: presented in a small 2- to 5-celled poricidal, hemispheric to turbinate capsule, dehiscing apically among styles, apex projected or truncate. Seeds numerous per locule, small, fusiform or ellipsoid, winged or wingless; seed coat thin, with reticulate or striate veins.

DISTRIBUTION: scattered throughout eastern Asia, especially China and Japan, but found in many other countries in that region including Korea, Taiwan, Tibet, Philippines, Vietnam and as far south as Indonesia. They also inhabit large parts of the Americas, from the U.S. Northeast via Central America in countries such as Mexico and Costa Rica down to the Andes in Ecuador and Peru.

Hydrangea anomala (D.Don)

D. Don: Prodromus Florae Nepalensis, 211. 1825.

SYNONYMS: H. altissima, H. anomala var. sericea, H. glaucophylla var. sericea, H. glabra

Woody climber; branchlets and inflorescence sparsely pubescent with upwardly spreading hairs, 0.5mm long.

LEAVES: opposite, simple, ovate, cuneate, truncate, or cordate at base, acute or acuminate at apex, 6-15cm. long, 3.5-10.5cm wide, their length 1.5 to 2 times their width, sharply and uniformly serrate, glabrous except for scattered hairs or clumps of hairs along midvein on lower surface. Petioles from 10 to 100mm.

INFLORESCENCE: a flat-topped, several-branched cluster; involucral bracts lanceolate or ovatelanceolate, membranous; fertile flowers white; hypanthium 1.5-2mm long; calyx lobes 5, 0.5-0.9mm long; petals 5, 2-3mm long, united and falling as a cap before the stamens elongate, cap apiculate or rounded at apex; stamens 9-20, 3-5mm long, 3 to 4 times as long as styles; ovary inferior; styles 2 or 3, 1-1.3mm long; capsule glabrous, 2.5-4.5mm long, styles 1-3mm long; seeds 1.5-2mm long, 1-1.5mm wide, nearly round, winged all around; sterile flowers usually present, white, 3-5 sepals rounded, entire to irregularly serrated, 1-2cm in diameter.

SEEDS: Winged all around, compressed. Capsule truncate.

DISTRIBUTION: Woods and mixed forests in Japan from sea level to 2,000 meters, on Honshu, Kyushu and Hokkaido islands; in Korea on Dagelet and Quelpaert Islands; in the eastern Himalaya Mountains of northern India, from 1,200 to 2,500 meters, and in west central to east central China, from 600 to 3,800 meters.

Hydrangea arborescens (L.)

Carl Linnaeus: Species Plantarum, 1753. Collected by John Bartram in Pennsylvania in 1736 and described in Flora Virginica in 1739. J. Bartram sent shipments of H. arborescens to Peter Collinson who introduced this species to Britain in 1736.

SYNONYMS: H. a. var. australis, H. a. var. kanawhana, H. a. var. vulgaris, H. vulgaris.

An untidy, erect deciduous shrub, up to 3m, but usually around 1m high with straggling, weak branches strigose pubescent, or puberulent.

LEAVES: Opposite, simple, elliptic, ovate, cordate or rounded up to 200mm long and 150mm wide and acuminate at the apex; rounded, subcordate, or cuneate at base, serrate and deciduous. Upper surface dark green, glabrous with hairs on major veins; lower surface paler green glabrous, pilose or tomentose, veins puberulous. Petiole up to 70mm.

INFLORESCENCE: Buds imbricate, 4- to 6-scaled, divergent and glabrous. A relatively flat or slightly rounded corymb, up to 150mm across comprising numerous small, whitish fertile flowers and fewer large sterile flowers comprising 3 to 4 (usually 4) entire sepals on short or long pedicels. Fertile flowers can be fragrant; hypanthium 0.8-1mm long; calyx lobes 5, deltoid, 0.5mm long; petals 5, oblong, 2 mm. long, falling separately; stamens 10, 1.5-4mm long, the 5 longer ones about twice as long as the shorter ones, filaments white, anthers white; ovary inferior; styles 2, or rarely 3, white, 1mm long. Sterile flowers white, sometimes absent, usually 4-lobed, occasionally 3-lobed, lobes ovate or orbicular, 8-15mm in diameter, pubescent.

SEEDS: The seed capsule 2-2.5mm long, 2-3mm wide at apex, somewhat conical at apex, styles 1.2-1.5mm long, ribs of capsule 8, 9 or 10, conspicuous; seeds elliptical, blunt at ends, 0.5-0.8mm long, 0.4-0.6mm wide, prominently striate.

DISTRIBUTION: Native to eastern USA.

Hydrangea arborescens ssp. radiata (Walter)

E.M. McClintock 1956

SYNONYMS: H. radiata Walter, H. nivea Michaux, H. cinerea.

LEAVES: Opposite, simple, ovate to oval, acuminate, serrate and deciduous. Upper surface dark green, glabrous with hairs on major veins. The lower epidermis is hidden beneath a thick silvery-white pubescence or indumentum, tomentose, the hairs being without tubercles.

INFLORESCENCE: A fragrant, slightly rounded corymb, up to 150mm across, comprising numerous white sterile flowers, of 3 to 5 sepals, on long pedicels.

SEEDS: The capsules, dry when mature, are poricidally dehiscent, spreading seeds from holes along the sides. The seeds are small, 0.5 to 0.7mm in length, ovoid to ellipsoid and with distinctive longitude ribs which often bear regular constrictions along their side walls.

DISTRIBUTION: Native to the southern Appalachians, eastern USA.

Hydrangea aspera D. Don

D. Don: Prodromus Florae Nepalensis, 211. 1825.

Shrub or small tree, 1-4m tall; branchlets and inflorescence pubescent with stiff and upwardly appressed or curling and erect hairs.

LEAVES: variable in shape, lanceolate to ovate, broadly ovate or deltoid, the lanceolate or ovate ones cuneate or rounded at base, 5-35cm long, 1.5-15cm wide, their length 2.5 to 7 times their width, serrate or serrulate along margin, petioles 0.5-6.5cm long, the broadly ovate or deltoid ones rounded or cordate at base, 10-25cm long, 7-17cm wide, serrate or doubly serrate along margin, petioles 4-21cm long; vesture on lower leaf surface variable and similar to that of stem.

INFLORESCENCE: a flat-topped, many-branched cluster, 10-30cm broad; bracts lanceolate, densely hairy on outer surface, glabrous on inner, caducous or remaining; fertile flowers white or blue, numerous, hypanthium 1-1.5mm long; sepals 5, 0.4-0.5mm long; petals 5, 2-2.5mm long, truncate at base, deciduous before stamens; stamens 10, 2-7mm long, usually alternately long and short; ovary completely inferior; styles 2, 3 or 4, 0.5-1.5mm long, sterile flowers always present, white, 4-lobed, lobes 1-3.5cm long, usually slightly longer than wide, with entire or fimbriate margins.

SEEDS: elliptical, 0.7-0.8mm long, 0.3-0.4mm wide, tapering at each end into minute tail-like extensions, capsules 3-5mm long.

DISTRIBUTION: In woods or thickets, eastern Himalaya Mountains from 1,500 to 2,300 meters; western China from 700 to 4,000 meters; central and eastern China from 250 to 2,100 meters; Formosa, Sumatra and Java from 1,000 to 2,500 meters.

Hydrangea heteromalla D. Don

D. Don: Prodromus Florae Nepalensis, 211. 1825.

SYNONYMS: H. vestita, H. sungpanensis, H. mandarinorum, H. khasiana, H. h. var. parviflora, H. dumicola, H. bretschneideri var. setchuensis.

Much branched shrub or small tree, 0.5 to 7m tall; branchlets and inflorescence pubescent with upwardly appressed hairs 0.5-1mm long.

LEAVES: ovate, often broadly so, 8.5-21.5cm long, 3-14cm wide, 1.5 to 3 times as long as wide, lower surface pubescent with varying amounts of hairs from sparse to dense enough to cover surface of leaf, or sometimes nearly glabrous with hairs along veins only; upper surface with a few scattered hairs or glabrous; petiole 2.5-4cm long, pubescent as the stem.

INFLORESCENCE: a rounded, many-branched cluster, 8-30cm broad; bracts linear to lanceolate, chartaceous, 1-3em long, 2-5mm wide, few pili on back and along margins; fertile flowers white, numerous; hypanthium 0.7-1.5mm long; calyx lobes 5, deltoid, 0.8-3mm long; petals 5, 2-3.2mm long, 1mm wide, ovate, falling separately; stamens 10, rarely 12, 2-6mm long, filaments broadened toward base; ovary half superior; styles 3 or 4, 1.5-2mm long, united for 0.5-0.8mm; capsules 4-5.5mm long, hypanthium 1.5-3mm long, styles 2-3.2mm long, united for 1-2.2mm, about half to threequarters of their length; sterile flowers always present, white, sepals 4, 1-3cm in diameter.

SEEDS: 1.5-2mm long, elliptical, tapering at each end into minute tail-like extensions.

DISTRIBUTION: Nepal, northeastern China, and the Himalayas.

Hydrangea integrifolia Hayata

Hayata: Journal College of Science, Imperial University, Tokyo, 22:131. 1906.

SYNONYMS: H. cuneatifolia, H. glandulosa, H. integra.

Evergreen woody climbers or shrubs, pubescence on inflorescence of coarse stellate hairs (0.15-0.25mm long) borne on short (0.05mm long) epidermal papillae, pubescence on stem dense, of fine stellate hairs with occasionally coarser hairs interspersed.

LEAVES: coriaceous, oval, 5-18cm long, 3-9cm wide, 1.5 to 3.5 times as long as wide; margins entire to remotely denticulate; upper surface glabrous; lower surface mostly glabrous except for occasional scattered coarse hairs and clusters of fine hairs in the axils of the secondary veins.

INFLORESCENCE: flowers white; sterile flowers present; hypanthium 0.8-1.3mm long; calyx lobes -1 or 5, 0.2-0.3mm long; petals 4 or 5, 1.4-2.2mm long; stamens 8-10, 1.5-4mm long; styles two or three, 0.8-1.2mm long during anthesis, clavate.

SEEDS: capsules 1.5-2.5mm long, fruiting styles 1.5-2mm long. It is further characterized by having both sterile and fertile flowers which are white, and fertile flowers which have 4 or 5 sepals and petals and 8 or 10 stamens. These characters are also found in H. seemannii, so that even though H. seemannii and H. integrifolia are widely separated geographically, they resemble each other very closely.

DISTRIBUTION: Philippine Islands and Taiwan.

Hydrangea involucrata Siebold

Nova Actorum: Academia (caesarea) Leopoldino-Carolina German. Nat. Cur. 14(2): 691. 1829.

SYNONYMS: Hydrangea longifolia Hayata.

Shrub, 1-2m tall; branchlets, inflorescence and pedicels pubescent with upwardly appressed hairs 0.5mm long.

LEAVES: ovate, 10-26cm long, 5-17cm wide, their length 1.5 to 2.5 times their width; both surfaces pubescent with appressed hairs; petiole 1.5-8mm long.

INFLORESCENCE: rounded, compound, many-branched; involucral bracts subtending the inflorescence, 1.5-2.5cm long, broadly obovate, pubescent with upwardly appressed white hairs on outside, glabrous on inside, caducous, leaving a row of scars at base of inflorescence when falling; in addition, a few bracts, ovate or lanceolate in shape, are scattered through the inflorescence; fertile flowers lavender, hypanthium 1.2-1.5mm long; calyx lobes 5, deltoid, 0.2-0.6mm long; petals 5, 2-3mm long, truncate at base; stamens 10, rarely 11 or 12, 3.5-6mm long; ovary inferior; styles 2 or 3, 1-2mm long; capsules 3-4mm long, pubescent, styles 2-2.5mm long; seeds elliptical, 0.8-1mm long, tapering at each end into minute tail-like extensions; sterile flowers always present, lavender, 4-lobed, lobes rounded, 1-3cm in diameter.

DISTRIBUTION: Japan, Taiwan.

Hydrangea macrophylla (Thunb.) Ser. (1830)

Initially described by Carl Peter Thunberg and named as Viburnum macrophyllum in his book Flora Japonica (1784). The description was revised, and the plant renamed Hydrangea macrophylla, by Nicholas Charles Seringe (1776-1858) in Prodromus Systematis Naturalis Regni Vegetabilis 4: 15. (Sept 1830) published by Augustin Pyramus de Candonelle.

SYNONYMS: H. hortensis, H. hortensia, H. otaksa, H. maritima, H. opuloides, H. macrophylla ssp. macrophylla.

Shrub rounded, up to 2.5m x 4m in mild climates, usually much smaller, shoots glabrous or pubescent with upwardly curled hairs, stout.

LEAVES: Simple, deciduous, opposite, up to 20cm long and 13cm wide, petiole 1-4cm long, cuneate, lamina broadly ovate or obovate, cuneate, acuminate, coarsely serrate, upper surface lustrous green, lower surface matt, strongly ribbed with reticulate venation. Bracts none.

INFLORESCENCE: in flat multi-branched corymbs (lacecaps) normally about 12cm across, but often much larger. In cultivated varieties the corymbs can be hemispherical or spherical. The corymbs comprise small fertile flowers (complete) and larger, showy, sterile flowers (often referred to as ‘ray florets’ and usually comprising only sepals). The petaloid sepals, broadly-elliptic to obovate, entire or serrate, can be 3-5 in number with some cultivars having many more and 1-2cm long. The actinomorphic fertile flowers and the ray florets can be various shades of white, pink or blue in colour. Fertile flowers: hypanthium 1.2-2mm long; calyx lobes 5, deltoid, 0.5-1mm long; petals 5, 2-3mm long, reflexed before falling; stamens 10, 2-6mm long; styles usually 3, occasionally 2, 4 or 5, 1-2mm long, in early anthesis free to base, ovary then inferior; styles in late anthesis united for 0.3-1mm from base, ovary then half superior; base of ovary and capsule, sometimes tapered toward pedicel; capsule (including styles) 2.5-8mm long, hypanthium 1.5-5mm long, styles 1.2-3.5mm long, free portion of styles 0.7-1.5mm, united portion of styles 0.5-2mm long; seeds 0.5-0.7mm long.

SEEDS: presented in a small 2- to 5-celled poricidal, subglobose capsule, 5mm long, many seeded, opening at top; seeds 0.5-0.7mm long.

DISTRIBUTION: Mainly Japan and Korea but also eastern Himalayas, north-east Burma and western China.

Hydrangea macrophylla ssp. serrata (Thunb.) Seringe. Makino.

Makino in Journal of Japanese Botany 6(7):11 1929.

SYNONYMS: H. serrata, H. thunbergii, H. yesoensis, H. cuspidata. H. serrta f. macrosepala.

A small entomophilous, deciduous, upright shrub, rarely exceeding 1.5m. Similar characteristics to H. macrophylla with similar cultivation, propagating and pruning requirements and some cultivars also share the ability to change colour from pink to blue depending on the availability of aluminium in the soil. Branchlets, leaves, and inflorescence glabrous or pubescent with upwardly appressed hairs.

LEAVES: 5.5-15cm long, 3-6cm wide, their length 1.5 to 3 times their width, ovate, acute or acuminate at apex; petioles 1-3cm long.

INFLORESCENCE: a flat-topped slightly convex corymb, 5-10cm across, with sterile flowers almost always present. Hypanthium 1.2-1.3mm long; calyx lobes 5, 0.5-0.6mm long; petals 2-3mm long; stamens 2-5mm long; styles usually 3, occasionally 2 or 4, 1-1.7mm long in early anthesis; styles united for 0.3-1mm from base in late anthesis.

SEEDS: in capsule (including styles) 2.5-5 (rarely 6) mm long, united for 0.5-1.5mm, free portion of styles 0.7-1.5mm long.

DISTRIBUTION: Japan and southern Korea, in woods and forests usually in mountainous areas, at elevations of 70 to 1,500 meters

Hydrangea paniculata Siebold

Siebold Nova Actorum: Academia (caesarea) Leopoldino-Carolina German. Nat. Cur. 14(2): 691. 1829.

SYNONYMS: H. kemienskii, H. sachalinensis, H. schindleri, H. verticillata.

Much branched shrub or small tree, 0.5-7m tall; branchlets and inflorescence pubescent with upwardly appressed hairs 0.3-0.5mm long.

LEAVES: opposite or ternate, deciduous, ovate, 7-15cm long, 3-10cm wide, 1.5 to 2.5 times as long as wide, both surfaces with scattered hairs along veins and veinlets; petiole 1-2.4cm long.

INFLORESCENCE: a compound, much branched, pyramidal cluster, 7-25cm long, lowermost branches of inflorescence opening first; bracts numerous, linear to ovate, chartaceous, 1-10mm long, 0.2-2.5mm wide, subtending main branches of inflorescence, reduced upward, few pili on back and along margins; fertile flowers white, very numerous; hypanthium 0.8-1mm long, glabrous or with few scattered hairs; calyx lobes 5, 0.5-1mm long; petals 5, 2-3mm long, ovate, reflexed before falling; stamens 10, 1.7—4.8mm long, filaments gradually broadening toward base; ovary half superior; styles 2, 3, or 4, 1.5-2mm long, united at base for 0.5-1.5mm, free for 0.5 to 1.2mm.

SEEDS: capsule 3.5-5mm long, hypanthium 1.5-3mm long, styles 2-3.5mm long, united for 1.3 to 2mm, about half to threequarters of their length; seeds 1.7-3mm long, 0.4-0.5mm wide, linear, tapering at each end into minute tail-like extensions; sterile flowers always present, white, 4-lobed, lobes ovate, 1.2-2cm long, 0.8-1.5cm wide.

DISTRIBUTION: Southeastern China, islands of Kyushu, Honshu and Hokkaido in Japan. Hydrangea paniculata is distinguished from the other Asiatic species of the section Hydrangea by its pyramidal inflorescence. This type of inflorescence is found elsewhere in H. quercifolia of the eastern United States. In flower and fruit H. paniculata is most like H. heteromalla; in fact, in regard to these characters, the two are almost indistinguishable, their only difference being the somewhat longer calyx lobes and the somewhat smaller seeds of H. heteromalla. Both have a half superior ovary with the styles united for one-half or more of their total length and alternately long and short stamens with filaments broadened toward their bases. H. paniculata is a fairly uniform species, showing no particular variation in any of its parts throughout its geographical range.

Hydrangea petiolaris (Siebold & Zuccarini), McClintock 1956

SYNONYM: Hydrangea anomala ssp. petiolaris (Siebold & Zuccarini) E. M. McClint. E. M. McClintock, Journal Arnold Arboretum, 37 : 373. 1956. H. scandens, H. tileaefolia, H. cordifolia, H. bracteata.

Hydrangea petiolaris is a vigorous woody climbing plant, growing 9 to 15m height and 2 to 2.5m wide. It grows up trees and rock faces in its native Asian habitats, climbing by means of small aerial roots on the stems.

LEAVES: The leaves are deciduous, ovate, 4–11cm long and 3–8cm broad, with a heart-shaped base, coarsely serrated margin and acute apex.

INFLORESCENCE: The flowers are produced in flat corymbs 15–25cm diameter in mid-summer; each corymb includes a small number of peripheral sterile white flowers 2.5-4.5cm across, and numerous small, off-white fertile flowers 1–2mm diameter with 15-20 stamens.

SEEDS: The fruit is a dry urn-shaped capsule 3–5mm diameter containing several small winged seeds.

Hydrangea quercifolia W. Bartram 1790

SYNONYM: H. plantanifolia, H. radiata

American botanist William Bartram discovered this plant in Georgia, USA, and made the first botanical description of it in his book Travels (1791). The species name is derived from the Latin words quercus ‘oak’, and folium ‘leaf’.

Stout erect shrub, much branched from base, 1-2m tall; young branchlets and petioles densely tomentose with long, reddish hairs; branches of inflorescence pilose with short, coarse hairs.

LEAVES: simple and opposite, suborbicular or oval in outline, 8-25cm long, mostly 5-lobed, the lobes coarsely serrate, petioles one-eighth to one-third as long as blades; upper leaf surface glabrous; lower leaf surface pilose or tomentose with two kinds of hairs — short, coarse, tubercular ones, and longer, fine, smooth ones which form an intertwining network. Petioles up to 8cm in length.

INFLORESCENCE: a compound, much branched cluster, pyramidal in shape, 15-25cm long; peduncle and axis puberulent to tomentose, fertile flowers white, very numerous; hypanthium 1-1.5mm long; calyx lobes 5, deltoid, 0.5-0.8mm long; petals oblong, acute, concave, 2-2.5mm long; stamens 10, 3-6mm long; styles 2, 3, or 4, 1-1.4mm long, somewhat thickened toward apex. Filaments greenish-white, to 8mm long, glabrous. Anthers biglobose, whitish, 1.2mm broad. Sterile flowers present, usually a single one terminating each lateral branch of the inflorescence, four sepals, sepals orbicular, 10-15mm in diameter.

SEEDS: capsules 1.5-2.5mm long, 2-2.5mm wide at apex, apex truncate, ribs 7 or 8, inconspicuous; styles 1.2-1.5mm long; seeds elliptical, 0.7-0.8mm long, 0.3-0.4mm wide, prominently striate, blunt at each end.

DISTRIBUTION: Southeastern United States States (Georgia, Florida, Alabama, Missouri). Hydrangea quercifolia is remarkably uniform throughout its range. It is characterized by its pyramidal inflorescence and its lobed leaves, by which characters it is distinguished from H. arhorescens. In geographic distribution these two species differ, although they overlap in part in the southern part of the range of H. arhorescens. Hydrangea quercifolia is found chiefly in the area of the Piedmont and coastal plain of western Georgia, Alabama, and Mississippi.

Hydrangea aspera ssp. sargentiana (Rehder) McClintock

SYNONYM: Hydrangea aspera D. Don ssp. sargentiana (Rehder) MeClintock, Journal Arnold Arboretum, 37:373. 1956. Hydrangea sargentiana Rehder, Plantae Wilsonianae, 1:29. 1911.

A deciduous shrub of bushy habit, up to 3m high, young shoots very stout, ribbed, and thickly clothed with stiff transparent bristles and small erect hairs, giving the shoot a remarkable, somewhat mossy aspect.

LEAVES: large, ovate, base rounded or cordate, shortly pointed, to 25cm long, to 8cm wide, dull green above, pale, bristly beneath, petioles bristly to 10cm long. Stem, lower leaf surface along midveins, and petioles velutinous, and in addition, interspersed with conspicuous, fleshy trichomes, 2-5 mm. long, split at apex.

INFLORESCENCE: flattish corymbs, to 25cm across, with pinkish-white sterile florets, 30mm wide at margins, fertile flowers rosy-lilac. Peduncles and pedicels downy and bristly.


Hydrangea seemannii L. Riley

Riley: Kew Bulletin, 207. 1924. Named after Berthold Seeman, a German botanist and plant hunter of the 19th century.

SYNONYM: H. peruviana.

Evergreen climbers, clinging by adventitious aerial roots; branchlets ferruginous pubescent with stellate hairs about 0.3mm long. A vigorous grower, has been known to achieve 15m in height.

LEAVES: evergreen, coriaceous, oval, 5-20cm long, 1.5-6cm wide, about 3 times as long as wide; upper surface glabrous, lower with few stellate hairs; margins entire; petioles 1-5cm long.

INFLORESCENCE: bracts few, broadly ovate, at base of inflorescence, enveloping the unopened inflorescence, leaving noticeable scars on falling. Inflorescence corymbose, glabrous; fertile flowers white; hypanthium 1.5mm long; calyx lobes 4 or 5, 0.2-0.3mm long; petals 4 or 5, 2mm long, 1mm wide; stamens 8 or 10, 2.8mm long; styles 2 or 3, 1mm long during anthesis, clavate; ovary inferior. Sterile flowers usually present, white.

SEEDS: capsule truncate at apex; 2.5mm long, 3.5mm wide, seeds elliptical.

DISTRIBUTION: Durango, in the Sierra Madre Occidental, Mexico, at approximate elevations of 2,000-2,600 meters.

References (print)

Curtis’s Botanical Magazine, London. 1787-1947. 164 volumes.
W. J. Bean, Trees and Shrubs hardy in the British Isles, 2nd Edition, John Murray, 1919,
Fred J. Chittenden, The Royal Horticultural Society Dictionary of Gardening, Oxford University Press, Oxford, 1951.
Wei Zhaofen (Wei Chao-fen), Bruce Bartholomew; Flora of China,
Elizabeth McClintock, A Monograph of the genus Hydrangea, Proceedings of the California Academy of Sciences, Vol. XXIX, No. 5, pp 147-256, 5th November, 1957.
Michael A. Dirr, Hydrangeas for American Gardens, Timber Press, Oregon, USA, 2004.
C. J. van Gelderen and D. M. van Gelderen, Encyclopedia of Hydrangeas, Timber Press, Oregon, USA, 2004.
Toni Lawson-Hall and Brian Rothera, Hydrangeas, A Gardener’s Guide, Timber Press, Oregon, USA, 2005.

References (on-line)
‘The Royal Horticultural Society Horticultural Database’, available at

Line diagrams: Fred J. Chittenden, The Royal Horticultural Society Dictionary of Gardening, Oxford University Press, Oxford, 1951.