Group Scaled rhododendrons
The leaves are covered with scales, especially on the underside of the leaves (it seems that the underside of the leaf is covered with small dots). The leaves are evergreen, in some species they are semi-evergreen. In rhododendrons of this group, the leaves at the base and at the end are more pointed, smaller and at the ends of the shoots are located less frequently than in other groups.
Daurian rhododendron (Rhododendron dauricum)
Homeland - Eastern Siberia (Sayan, Transbaikalia), the Far East, Northeastern Mongolia, Northeastern China. Deciduous (some of the leaves remain overwintering, curled up in tubes), highly branched shrub up to 0.5–2 m high (we have 3 m). Leaves are elliptical or oblong-obovate, 1.2–3.3 (5) cm long, mostly obtuse, less often acute, often notched with a short spine, densely covered with scaly glands, but without bristly hairs, shiny and aromatic. Flower buds 1 (2-3), flowers appear before the leaves open. Corolla light pink, with a lilac shade, rarely white, 1.4–2.2 cm long and 2.3–3 (4) cm in diameter, with non-overlapping obovate lobes making up 2/3 of the corolla length ... Blooms in April – May. The seeds ripen.
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Relatively winter-hardy, sometimes the ends of annual shoots freeze slightly, flower buds are damaged in severe winters, but it suffers more from winter thaws and spring frosts. Tested 7 samples, now in collection 3, received in 1941, 1981 and 1994. from nature (Khabarovsk Territory).
Spiky rhododendron (Rhododendron mucronulatum)
Homeland - the Far East, Korea, Northeast China, Japan. Semi-evergreen or deciduous shrub up to 1-3 m high (we have 2 m). Leaves are elliptical and oblong-elliptical, (2) 3–8 cm long and (0.8) 1.2–2.5 cm wide, on sterile shoots up to 4 cm long, with a pointed or sharp tip with a short calloused thorn, on top and along the edges with bristly hairs, along the edges with scale-like glands, shiny and fragrant. Flowers appear before the leaves open. Flower buds (1) 3–6, 1 (2) -flowering, at the ends of the shoots. Corolla light, lilac-pink, rarely white, 2.2–3.3 cm long and 3.5–5 cm in diameter, funnel-bell-shaped, with overlapping wavy lobes that are 1/2 of the corolla length. Blooms in April – May. The seeds ripen.
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Relatively winter-hardy, sometimes the ends of annual shoots freeze slightly, flower buds are damaged in severe winters, but it suffers more from winter thaws and spring frosts. Tested 13 samples, now in collection 2, received in 1990 and 1999. from GBS (Moscow).
Group Fringed Hairy Rhododendrons
The leaves are deciduous, soft (with rare exceptions), 2–10 cm long, covered with fringed hairs above and below, or glabrous. In addition to fringed hairs, glandular hairs are also found.
Albrecht's rhododendron (Rhododendron albrechtii)
According to the modern classification, it does not have the status of a separate species, but the species has not yet been precisely determined.
Homeland - Central and Northern Japan. Deciduous shrub up to 1.5 m high (we have 0.8 m). Young shoots are glandular pubescent, later bare, purple-brown. Leaves, 5 at the ends of the shoots, oblong-ovate or lanceolate, 4–12 cm long, pointed, ciliate at the edges, sparsely pubescent. Flowers 4-5, bloom before shoots appear or at the same time. Corolla broadly campanulate, purplish red, 10 stamens, the same length as corolla. Blooms in May. The seeds do not ripen regularly.
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Not very winter-hardy, sometimes the ends of annual shoots freeze slightly, suffers from frost, perennial wood is damaged in severe winters. 6 samples have been tested, now in collection 1, obtained in 1981 from the Novy Dvor arboretum (Opava, Czech Republic).
Rhododendron Vasey (Rhododendron vaseyi)
Homeland - North America.Deciduous, irregularly branched shrub up to 5 m high (we have 1.5 m). Young shoots are slightly pubescent, red-brown. Leaves are elliptical or oblong, 5–12 cm long, up to 4 cm wide, pointed, slightly wavy at the edges, ciliate, dark green above, glabrous on both sides or sparsely pubescent along the main vein. Flowers 5–8, bloom to leaves. The corolla is pink, bell-shaped, with a short tube. The column is longer than the stamens. Blooms in May – June. The seeds ripen.
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Winter-hardy, in severe winters the ends of annual shoots freeze slightly. Tested 6 samples, now in collection 5, received in 1980-1993. from, Kiev (Ukraine), Tallinn (Estonia) and Rogov (Poland).
The form ‘Album’ – corolla is white with red specks in the pharynx. Flowering time and winter hardiness and autumn color as in the original species. There is 1 sample in the collection, obtained from Salaspils (Latvia).
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Rhododendron tree (Rhododendron arborescens)
Homeland - the east of North America. Deciduous shrub up to 3 (6) m (we have 0.9 m). Young shoots are naked. Leaves are obovate or elliptical, 3–8 cm long, sharp or obtuse, ciliate at the edges, bright green, shiny, grayish below, glabrous. Flowers 3-6, very fragrant, bloom after the full development of the leaves. The corolla is white or pinkish, up to 5 cm in diameter, outside, like the calyx, glandular hairy, with a cylindrical tube expanding upward, up to 3 cm long, longer than the limb, 5 stamens, longer than the corolla. Blooms in June – July. The seeds ripen.
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Winter-hardy, in severe winters the ends of shoots and flower buds freeze slightly. Tested 5 samples, now in collection 3, received in 1995-1998. from Moscow, Yoshkar-Ola, Tarandt (Germany).
Rhododendron yellow (Rhododendron luteum)
Homeland - the center and south of Europe, the Caucasus, Asia Minor. Deciduous densely branched shrub up to 2 (4) m high (we have 1.7 m). Young shoots are glandular hairy. Leaves are oblong-lanceolate, 4–12 cm long, up to 4 cm wide, with a pointed tip, narrowed towards the base, finely serrate and ciliate along the edges, with scattered bristly hairs on both sides. Flowers 7-12, very fragrant. Corolla yellow or orange-yellow, with a darker spot, up to 5 cm in diameter, funnel-shaped, with a narrowly cylindrical tube, sharply turning into a limb. The stamens are curved, 2 times longer than the tube, the column is longer than the stamens. Blooms in May – June. The seeds ripen. The foliage is brightly colored in autumn.
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Relatively winter-hardy, sometimes the ends of annual shoots freeze slightly, flower buds and perennial wood suffer in severe winters. Tested 11 samples, now in collection 9, received in 1936–90. from Moscow, Barnaul, from the nature of the Caucasus, Bratislava (Slovakia).
The form ‘Macranthum’ - flowers with a diameter of up to 6.5 cm, height 1.5 m, flowering time and winter hardiness as in the original species, the seeds ripen. Tested 2 samples, now in collection 1, received in 1979 from Bratislava (Slovakia).
Kamchatka rhododendron (Rhododendron camtschaticum)
Homeland - the extreme north of Siberia, the Far East, Northern Japan, northwest of North America. Low deciduous shrub up to 35 cm high (we have 20 cm), with rough branches. Leaves are ciliate along the edge, obovate, almost sessile, 2–4 cm long. Flowers 1-2 (3) on peduncles up to 10 cm long. Corolla purple, up to 5 cm in diameter, wheel-shaped, deeply dissected, with a short tube. Blooms in June. Seeds ripen.
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Relatively winter-hardy, flower buds suffer in severe winters. Damaged by frost. Tested 3 samples, now in collection 2, received in 1981 and 1998. from Kiev and St. Petersburg.
Rhododendron canadian (Rhododendron canadense)
Homeland - the east of North America, in river valleys, swampy forests. Deciduous, branched shrub up to 1 m high, with a dense crown. Young shoots are pubescent, reddish-yellow, later grayish-brown. Leaves are elliptical, 2–4 (6) cm long, pointed, ciliate at the edges, dull blue-green, thinly pubescent. Flowers 3-7, bloom to leaves.Corolla pink-purple, 1.5-2 cm long, two-lipped, with a lower lip, dissected almost to the base, 10 stamens. Blossoms in May. The seeds ripen.
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Winter-hardy. Tested 7 samples, now in collection 6, received in 1979-1988. from Moscow, Kiev (Ukraine), Berlin and Tarandt (Germany), Bratislava (Slovakia), Basel (Switzerland).
‘Albiflorum’ - a rare form with white flowers. Height 0.5 m, flowering time and winter hardiness as in the original species. The collection contains 2 samples, obtained in 1989 and 1993. from Salaspils (Latvia).
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Rhododendron sticky (Rhododendron viscosum)
Homeland - the east of North America. Deciduous shrub up to 1.5–3 (5) m high (we have 1.5 m). Young shoots are finely bristly. Leaves are ovate, ovate-lanceolate, 2–6 cm long, acute or obtuse, wedge-shaped at the base, ciliate at the edges, dark green above, usually glabrous, lighter below, finely bristly along the main vein. Flowers 4-9, fragrant, bloom after the full development of the leaves. Corolla white or pinkish, about 3 cm in diameter, funnel-shaped, finely glandular outside, with a cylindrical weakly expanded tube 1.5 times longer than the limb, 5 stamens, much longer than the corolla. Blooms in June – July. The seeds ripen. The foliage turns red in the fall.
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Relatively winter-hardy, sometimes the ends of annual shoots freeze slightly, flower buds and perennial wood suffer in severe winters. Tested 5 samples, now in collection 4, received in 1980-1996. from Rogov (Poland), Tarandt (Germany) and Kamon arboretum (Szombathely, Hungary).
Koster's Rhododendron (Rhododendron x kosterianum – hybrid R. japonicum x R. molle)
A group of hybrids distinguished by the purity and brightness of the color of the flowers (see also hybrids Nos. 43-19 and 43-20) and leaves with slightly pubescent underneath. Height up to 1.5 m (we have 1-1.3 m). Blooms in May – June.
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Quite winter-hardy, the ends of annual shoots can freeze slightly, in severe winters - to perennial wood. Tested 8 samples, now in collection 5, received in 1979-1988. from Arboretum Novy Dvor (Opava, Czech Republic), Bratislava (Slovakia), Leiatsig (Germany) and St. Petersburg.
Rhododendron hybrid No. 43/19
(R. Hybrid No. 43/19, free pollination hybrid R. x kosterianum)
Erect bush 1.1 m high. Inflorescence 12-13 cm in diameter consists of 6-9 flowers with a weak aroma. The flower is very large, with a wide funnel-shaped tube, the corolla length is 6–6.4 cm, the diameter is up to 9 cm. The buds are pink, the flowers are pale pink with a beautiful dark orange-red speck on the upper petal, from the outside along the edge of the petal to the middle there is a white stripe ...
Blooms in June.
The seeds ripen.
The collection contains 1 specimen, a reproduction of 1988 of the specimen obtained from the Novy Dvor arboretum (Opava, Czech Republic).
Rhododendron hybrid No. 43/20
(R. Hybrid No. 43/20, hybrid of free pollination R. x kosterianum)
Erect bush 1.1 m high. Inflorescence 12 cm in diameter consists of 7-8 flowers with a weak aroma. The flower is very large, with a wide funnel-shaped tube, the corolla length is 7 cm, the diameter is up to 9-9.5 cm. The flowers are salmon-pink with bright orange specks inside the corolla, bright orange spots in the middle of the petals. Blooms in June. The seeds ripen.
The collection contains 1 specimen, a reproduction of 1988 of the specimen obtained from the Novy Dvor arboretum (Opava, Czech Republic).
About other hybrids with the participation of R. Koster - in the article Hybrid rhododendrons.
Rhododendron marigold (Rhododendron calendulaceum)
Homeland - the east of North America.
Deciduous shrub up to 1–3 (5) m high (we have 1.5 m) with straight, open branches. Young shoots are finely pubescent and bristly hairy. Leaves are broadly elliptical, 4–8 cm long, pointed, finely pubescent along the edges. Flowers usually 5-7, bloom at the same time with the leaves.
The color of the corolla varies from yellow, yellow-orange to salmon and scarlet with a darker spot of stamens 5, longer than the corolla.
Blooms in May – June. The seeds ripen.
Winter-hardy, in severe winters the ends of annual shoots freeze slightly.
Tested 8 samples, now in collection 3, received in 1981, 1984 and 1998. from New York (USA), Riga and Salaspils (Latvia).
Rhododendron pink (Rhododendron roseum)
Homeland - North America.
Deciduous shrub up to 3 (5) m (we have 1, 6 m). Young shoots are weakly pubescent, buds are gray pubescent. Leaves are elliptical or oblong-ovate, 3–7 cm long, pointed, grayish-green above, grayish below, densely gray-pubescent. Flowers 5-9, fragrant. Corolla bright pink, rarely whitish, up to 1.5 cm in diameter, corolla tube 1.5–2 cm long, limb of the same length. The stamens are gracefully curved, 2 times as long as the tube, the column is longer than the stamens.
Blooms in May – June. The seeds ripen.
Winter-hardy, in severe winters the ends of annual shoots freeze slightly. The collection contains 3 specimens, obtained in 1980 and 1985. from arboretums Novy Dvor (Opava, Czech Republic) and Kamon (Szombathely, Hungary).
Rhododendron Schlippenbach (Rhododendron schlippenbachii)
Homeland - the Far East, Northeast China, Korea, Japan. Deciduous, spreadingly branched shrub up to 0.6–2 (5) m high (we have 1.2 m), with light gray bark. Young shoots are rusty glandular pubescent, later glabrous, brownish. The leaves are collected in 4-5 at the ends of the shoots, wedge-shaped obovate, 4-10 cm long, with a rounded apex, slightly wavy at the edges, dark green above, almost naked, hairy below along the veins. Flowers (1) 3–6, bloom with leaves or earlier. Corolla pale pink, with purple dots, 5–8 cm in diameter, 10 stamens, bent upward. Blooms in May – June. The seeds ripen.
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It is winter-hardy, but suffers from frost; flower buds freeze in severe winters. Tested 5 samples, now in collection 2, received in 1963 and 1987. from Vladivostok and Kiev.
Japanese soft rhododendron ( Rhododendron molle ssp. japonicum )
Homeland - Japan. Deciduous shrub up to 1 (2) m high. Young shoots are glabrous or with bristly hairs. Leaves are thin, oblong lanceolate, 4–10 cm long, obtuse with a pointed tip, from above with adpressed scattered bristly hairs, pubescent from below only along the veins. Flowers usually 5-7, bloom at the same time with the leaves. The color of the corolla varies from yellow, yellow-orange to salmon and scarlet with a darker spot, 5 stamens, longer than the corolla. Blooms in May – June. The seeds ripen.
Relatively winter-hardy, sometimes the ends of annual shoots freeze slightly, perennial wood can be damaged in severe winters. Tested 13 samples, now in collection 6, received in 1979-1993. from Moscow, Kiev, Rogov (Poland), arboretum Kamon (Szombathely, Hungary).
Forms:
‘Album’ - variation with white flowers and a dark yellow or greenish-yellow spot in the pharynx. Height 0.8 m, flowering time and winter hardiness as in the original species. The collection contains 3 specimens, obtained in 1980–1993. from Kiev (Ukraine), Rogov (Poland), Bratislava (Slovakia).
‘Aureum’ - a variation with golden yellow flowers and a yellow-orange spot in the throat. Height 1.3 m, flowering time and winter hardiness as in the original species. The collection contains 3 specimens, obtained in 1980–1993. from Kiev (Ukraine), Rogov (Poland), Salaspils (Latvia).
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Read also:
- Evergreen rhododendrons
- Rare rhododendrons
- Hybrid rhododendrons
Photo by the author
