Academic Centre
Rh. albrechtii Maxim.
Lax shrub 1-2,5 m high; young shoots at first rather densely setulose-glandular, later eglandular.
Leaves deciduous, in clusters of 5 at the end of branchlets, obovate or oblong-obovate; lamina 3,6-9 cm long, 1,3-4 cm broad; both surfaces rather densely strigose.
Petiole setulose-glandular.
Inflorescence 2-5 flowers, flowers opening before or with the leaves.
Corolla rotate-campanulate, 2,3-3,5 cm long, 3,5-5 cm across, red-purple, bright purplish-rose or deep rose, with olive-green spots.
Japan. 1,000-2,000 m.
Epithet: After Dr. M. Albrecht, Russian naval surgeon.
Rh. arborescens (Pursh) Torr.
Shrub 1-3 m or rarely small tree up to 6 m high; young shoots glabrous, not setulose.
Leaves deciduous, obovate, oblanceolate or oblong-lnceolate; lamina 3-8 cm long, 1,1-3 cm broad; upper surface bright green, glabrous, not strigose; underside pale green or glaucescent, glabrous.
Inflorescence 3-8 flowers, flowers opening after the leaves are developed, very fragrant.
Pedicel glandular.
Corolla tubular-funnel-shaped, 3,5-5,2 cm long, white or pink, with or without a yellow blotch.
Stamens 4,5-6 cm long, about twice as long as the corolla-tube.
Extends from New York and Pennsylvania to Georgia, Alabama, N and S Carolina, Kentucky and Tennessee. Up to and over 1,600 m.
Epithet: Becoming tree-like.
Rh. atlanticum (Ashe) Rehder
Low shrub, 30-60 cm high or rarely taller, stoloniferous; young shoots setulose.
Leaves deciduous, obovate or oblong-obovate; lamina 2,2-6,3 cm long, 1,2-2,2 cm broad; upper surface bluish-green or bright green, glabrous, not strigose; underside bright green or glaucescent, glabrous, not strigose, often glandular.
Inflorescence 4-10 flowers, flowers opening before or with the leaves, very fragrant.
Corolla tubular-funnel-shaped, 3,5-4,8 cm long, white. usually flushed pink or purple, without blotch, tube outside and middle of all the lobes glandular with long-stalked glands.
S Pennsylvania and Delaware to Virginia, N and S Carolina, and Georgia.
Epithet: From the Atlantic seaboard.
Rh. austrinum (Small) Rehder
Shrub up to 2,75 m high, or small tree 4,5 m high or more; branchlets pubescent, glandular.
Leaves deciduous, elliptic, oblong-obovate, obovate or ovate; lamina 3-9 cm long, 0,6-4 cm broad, both surfaces rather densely minutely pubescent, margin strigose.
Petiole pubescent, glandular.
Inflorescence 6-15 flowers, flowers opening before or with the leaves, fragrant.
Pedicel and calyx pubescent, glandular.
Corolla tubular-funnel-shaped, 3,2-3,4 cm long, yellow or orange, the tube usually purplish, without blotch.
Stamens 5-6 cm long, nearly twice as long as the corolla tube.
From N Florida, and the Georgia-Alabama coastal plain to SE Mississippi.
Epithet: Southern.
Rh. x bakeri (Lemmon ex Mckay) Hume
(Rhododendron flammeum x Rhododendron canescens)
Branching shrub to 3 m, ± colonial;
Leaves narrowly obovate, 3–6 cm, less than half as wide, full-grown at anthesis;
Flowers several in a short raceme, orange-red to red, 4 cm wide, the upper lobe of the cor much wider than the others and marked with a large orange spot; sep round-ovate, glandular-ciliate, scarcely 1 mm;
Cumberland Plateau region from E Kentucky. and W Virginia. to E Tennessee., N Georgia., and N Alabama.
Epithet: After Dr. W.F. Baker, Amory University, USA.
Rh. calendulaceum (Michx.) Torr.
Shrub 1-3 m or rarely up to 5 m high; young shoots pubescent and strigose, older branchlets glabrous.
Leaves deciduous, elliptic, oblong-obovate, oblanceolate or lanceolate; lamina 3,5-8 cm long, 1,3-3,5 cm broad, upper surface pubescent or strigose; underside rather densely or moderately pubescent or strigose.
Petiole densely pubescent, and strigose.
Inflorescence 5-8 flowers, flowers opening with or shortly after the leaves.
Corolla tubular-funnel-shaped, 2,5-4 cm long, yellow, yellowish-orange, orange, red or scarlet, with orange blotch, tube glandular outside, lobes glandular or eglandular.
Pennsylvania, W Virginia, N Carolina, Georgia.
Epithet: Like a Calendula.
Rh. canadense (L.) Torr.
Shrub 0,3-1,2 m high; young shoots puberulous, later glabrous.
Leaves deciduous, scattered, oblong, elliptic or oblong-oval; lamina 2-5,5 cm long, 0,6-2,3 cm broad, upper surface pale bluish-green, strigose; underside rather densely minutely puberulous (downy).
Petiole rather densely puberulous.
Inflorescence 3-6 flowers, flowers opening before the leaves.
Corolla rotate-campanulate, 1,6-1,8 cm long, 2-lipped, rose-purple.
Stamens 10.
From Labrador, Newfoundland, Quebec to New England, central New York, NE Pennsylvania and N New Jersey.
Epithet: From Canada.
Rh. canadnese f. albiflorum (Rand et Redfield) Rehder
Corolla white.
Epithet: With white flowers.
Rh. cumberlandense E.L.Braun
sin. Rh. bakeri (Lemon et McKay) Hume
Shrub 0,6-2 m high, or low forms 15 cm high, stoloniferous.
Leaves deciduous, obovate; lamina 3-7 cm long, 1,5-2,5 cm broad, upper surface dark green, glabrous or pubescent; underside more or less glaucous, glabrous to sparsely pubescent, eglandular.
Inflorescence 3-7 flowers, flowers opening after the leaves.
Corolla tubular-funnel-shaped, 2,5-4 cm long, 3,5-5 cm across, yellow, orange, reddish-orange or red, with orange-yellow blotch, outside densely puberulous, glandular.
From Kentucky to Georgia, Alabama and N Carolina.
Epithet: After Dr. W.F. Baker, Amory University, USA.
Rh. luteum Sweet
Shrub 0,6-3,6 m high, stoloniferous; young shoots setulose or not setulose, glandular with long-stalked glands.
Leaves deciduous, oblong, oblong-obovate or oblong-lanceolate; lamina chartaceous, 5-11 cm long, 1,3-4 cm broad, upper surface dark green or pale green, strigose-glandular; margin serrulate, strigose; underside strigose-glandular.
Inflorescence 7-12 flowers.
Corolla tubular-funnel-shaped, 3,2-4,5 cm long, yellow with a darker (yellow) blotch, flowers opening before the leaves, very fragrant.
Pedicel glandular, outside glandular, viscid.
Calyx glandular.
Stamens 5.
Caucasus, N Turkey, SW Russia, Georgia, Ukraine. Sea-level to 2,200 m.
Epithet: Yellow.
Rh. luteum v. glauca
Rh. molle ssp. japonicum Kron
sin. Rh. japonicum (A.Gray) Suringar
Shrub 0,6-1,8 m high, occasionally stoloniferous; young shoots setulose, eglandular.
Leaves deciduous, elliptic, obovate, oblong-obovate or oblanceolate; lamina chartaceous, 5-11,5 cm long, 1,8-3,5 cm broad, upper surface dark green, strigose, eglandular, margin strigose; underside pale green, not pubescent, not setulose, strigose only on the lateral veins, midrib strigose.
Petiole setulose.
Inflorescence 6-12 flowers, flowers opening before the leaves.
Pedicel setulose.
Calyx margin densely setulose.
Corolla widely funnel-shaped, 4,8-6,2 cm long, orange, yellow. salmon-red or brick-red, with large orange blotch.
Stamens 5.
Japan. Up to 1,000 m.
Epithet: From Japan.
Rh. molle ssp. molle
sin. Rh. molle (Bl.) G.Don
Shrub 0,3-1,2 m high; young shoots villous, eglandular.
Leaves deciduous, oblong, oblanceolate or oblong-lanceolate; lamina 6-15 cm long, 1,8-5,6 cm broad, upper surface often pubescent, eglandular; margin serrulate, strigose; underside often rather densely pubescent, eglandular.
Petiole often setulose, eglandular.
Inflorescence 6-12 flowers, flowers opening before or with the leaves.
Calyx minutely puberulous.
Corolla widely funnel-shaped, 4,3-5,6 cm long, golden-yellow, yellow or orange, with a large greenish blotch separated into dots.
E China, in Hubei, Zhejiang and Jiangsu.
Epithet: With soft hairs.
Rh. x mortieri
(Rhododendron calendulaceum x Rhododendron periclymenoides)
Rh. nipponicum Matsum.
Shrub 1-1,8 m high, bark shredding and exposing the polished reddish-brown stem and branches; young shoots glandular, later glandular or eglandular.
Leaves deciduous, obovate; lamina chartaceous, 5-17,5 cm long, 4-8,8 cm broad, upper surface bright green, adpressed-bristly; margin bristly; underside adpressed-bristly.
Petiole subsessile (scarcely stalked), leaf-base decurrent on the petiole.
Inflorescence 6-15 flowers, flowers from terminal buds, the leafy shoots from separate axillary (lateral) buds below, flowers opening with or after the leaves.
Pedicel pendulous.
Corolla tubular-campanulate, 1,5-2,4 cm long, 0,8-1 cm broad, white, or tube white and greenish, lobes flushed pink.
Stamens 10.
Central Japan. 900 m.
Epithet: From Japan.
Rh. occidentale (Torr. et Gray) A. Gray
Shrub 0,6-4,5 m high; young shoots glabrous or minutely puberulous.
Leaves deciduous, oblanceolate, lanceolate, oblong-lanceolate, obovate or elliptic; lamina 4-9 cm long, 1,5-3 cm broad, upper surface bright green or dark green, often minutely pubescent; margin rather densely strigose; underside often minutely pubescent, midrib strigose.
Inflorescence 5-12 flowers, flowers opening with or after the leaves, fragrant.
Calyx 1-6 mm long.
Corolla tubular-funnel-shaped, 4,2-5 cm long, white, pink, orange-pink, red or yellow, with or without stripes and spots, usually with yellow or orange blotch, outside villous, glandular.
From S Oregon to S California. Sea level up to 2,750 m.
Epithet: Western.
Rh. periclymenoides (Michx.) Shinners
Shrub 0,6-3 m high, occasionally stoloniferous; young shoots glabrous or sparsely pubescent, strigose, eglandular.
Leaves deciduous, elliptic, obovate or oblong; lamina chartaceous, 3-9 cm long, 1,3-3 cm broad; upper surface bright green, strigose or not strigose, midrib densely pubescent; margin strigose; underside green, strigose or not strigose, midrib strigose or not strigose..
Inflorescence 6-12 flowers, flowers opening before or with the leaves, fragrant.
Corolla tubular-funnel-shaped, 2,6-3,5 cm long, white, pale pink, pink or pinkish-purple, without blotch, outside pubescent, eglandular.
On the Appalachian Mountains, and extends from Massachusetts to N Carolina, W to Central New York, Pennsylvania, S Ohio, E Kentucky, E. Tennessee, N Georgia, N Alabama. Up to 1,150 m.
Epithet: Like honeysuckle.
Rh. pilosum (Michx. ex Lamarc) Craven
sin. Menziesia pilosa (Michx. ex Lamarc) de Jussieu ex Persoon
Rh. prinophyllum (Small) Millais
sin. Rhododendron roseum (Lois.) Rehder et E.H.Wilson
Shrub 0,6-4,5 m high, rarely stoloniferous; young shoots rather densely finely pubescent, strigose or not strigose.
Leaves deciduous, elliptic, obovate or oblong-obovate; lamina 3-7 cm long, 1,3-3 cm broad, upper surface bluish-green, villous; margin strigose; underside pale green, rather densely villous, strigose.
Petiole densely pubescent, strigose.
Inflorescence 5-9 flowers, flowers opening with the leaves, clove-scented.
Pedicel villous, glandular.
Corolla tubular-funnel-shaped, 2,8-3,5 cm long, pink or purplish-pink, rarely white, with or without brown-red blotch, flowers opening with the leaves, clove-scented; glandular.
Stamens about twice as long as the corolla-tube.
Extends from SW Quebec, through Massachusetts, Pennsylvania, SE Missouri and Tennessee to Virginia.
Epithet: With leaves like prinos.
Rh. quinquefolium Bisset et S.Moore
Shrub or small tree, 1,2-7,6 m high; branchlets glabrous, eglandular.
Leaves deciduous, in pseudowhorls of 4 or 5 at the end of the branchlets, broadly obovate, oval or broadly elliptic; lamina 3-5 cm long, 1,8-3 cm broad, upper surface pale green, often with a red-purple margin, glabrous; midrib pubescent; margin ciliate; underside pubescent towards the base or glabrous.
Petiole pubescent.
Inflorescence 1-3 flowers, flowers produced with the leaves from the same terminal bud.
Corolla rotate-campanulate, 2,3-2,8 cm long, 3-4,3 cm across, pure white with green spots.
Honshu and Shikoku (Japan). 700-1,500 m.
Epithet: Leaves in fives.
Rh. reticulatum D. Don ex G.Don
sin. Rh. rhombicum Miq.
Shrub or tree, 1-3 m high; young shoots densely adpressed-pilose, later glabrous, eglandular.
Leaves deciduous in whorls 2 or 3 at the end of the branchlets, broadly ovate or ovate or rhombic; lamina generally 3-7 cm long, 2-5 cm broad; upper surface dark green, later glabrous or almost glabrous; underside somewhat reticulate, pubescent or nearly glabrous.
Petiole pilose.
Inflorescence 1-2 rarely 3-4 flowers, flowers opening before the leaves.
Calyx minute, 0,5-1 mm long, pilose.
Corolla rotate-funnel-shaped, 2-2,8 cm long, 3,5-5 cm across, purple, rose-purple or reddish-purple, unspotted or with dark purple blotaches.
Stamens 10.
Honshu, Kyushu, Shikoku in Japan. 300-1,000 m.
Epithet: Netted, referring to the venation.
Rh. schlippenbachii Maxim.
Shrub 1-5 m high; young shoots glandular with long-stalked glands, later eglandular.
Leaves deciduous in pseudowhorls of 5 at the end of the branchlets, obovate; lamina 5-8,8 cm long, 3-6,8 cm broad, upper surface dark green, glabrous; underside pale green, glabrous, midrib pubescent.
Petiole flattened, glandular, glands long-stalked.
Inflorescence 3-6 flowers, flowers opening with or immediately before the leaves.
Pedicel rather densely glandular.
Corolla broadly rotate-funnel-shaped, 3-4 cm long, 5,6-8 cm across, pale to rose-pink or white, spotted red-brown.
Korea and the Korean archipelago, bordering parts of Russia and Japan. 400-1,800 m.
Epithet: After Baron A. von Schlippenbach, Russian naval officer and traveller.
Rh. vaseyi A. Gray
Shrub 1,5-4,6 m high; young shoots at first sparsely pilose, afterwards glabrous or glabrescent.
Leaves deciduous, scattered, elliptic, elliptic-lanceolate or oblong-lanceolate; lamina 5-12,5 cm long, 1,3-4,3 cm broad, apex acuminate; upper surface dark green, glabrous; margin strigose; underside light green, not setulose except midrib setulose.
Inflorescence 4-8 flowers, flowers opening before the leaves.
Pedicel glandular.
Corolla rotate-campanulate, 2,5-3 cm long, 3,5-3,8 cm across, 2-lipped, upper lip of 3 lobes, lower lip of 2 lobes, light rose or pale pink, with orange or reddish-brown spots.
Stamens 7.
N and S Carolina. 900-1,830 m.
Epithet: After G.R. Vasey (1822-1893), who discovered it in N Carolina in 1878.
Rh. viscosum (L.) Torr.
Shrub 1-4,5 m high, stoloniferous; young shoots setulose or strigose, eglandular.
Leaves deciduous, obovate, oblong-obovate or oblanceolate; lamina 1,5-7,3 cm long, 0,5-3,5 cm broad; upper surface dark green, usually glabrous; margin strigose; underside pale green or glaucescent, usually glabrous except midrib strigose.
Petiole setulose or strigose.
Inflorescence 3-9 flowers, flowers opening after the leaves are developed, spicy fragrance.
Pedicel setulose-glandular.
Calyx setulose-glandular or setulose.
Corolla slender, narrowly tubular-funnel-shaped, 3-4,5 cm long, white or sometimes white suffused with pink, tube setulose-glandular outside, lobes glandular along the middle.
Maine, Massachusetts, Connecticut to N Carolina, south eastern S Carolina, west to Ohio, SE Tennessee, Louisiana.
Epithet: Sticky.
