JARS v36n1 - A New Rhododendron Species and Four New Varieties

A New Rhododendron Species and Four New Varieties
H.H. Davidian, Edinburgh, Scotland

Rhododendron tubiforme (Cowan et Davidian), Davidian sp. nov.
Species R. glaucophyllo Rehd. affinis sed corolla tubulosa, 2.3-3.8 cm. longa, stylo longo gracili recto corollam aequante vel superante, habitu ad 2.14 m. alto differt.

Frutex rectus 30 cm.-2.14 m. altus, cortice levi brunneo desquamante, ramulis dense vel moderate lepidotis. Folia sempervirentia; lamina coriacea, obovata, oblongo-obovata, oblonga, lanceolata vel oblanceolata, aromatica, 3.2-6 cm. longa, 1.3-2.5 cm. lata, apice rotundata, obtusa vel acuta et mucronata, basi obtusa, cuneata vel rotundata, supra atroviridis nitens dense vel moderate lepidota, infra conspicue glauca, dense lepidota, squamis minoribus pallide flavidis inter se 1-2 vel non-nunquam 3 diametris distantibus, squamis majoribus atrobrunneis dispersis; petiolus 0.4-1 cm. longus, dense vel moderate lepidotus glaber. lnflorescentia terminalis, vel raro terminalis et foliis summis 1-2 axillare, umbellata vel breviter racemosa, 3-5-flora; rhachis 2-3 mm. longa, lepidota vel elepidota; pedicelli 0.8-1.6 cm. longi, corollae breviores, dense lepidoti. Calyx 5-lobatus, magnus, 5-8 mm. vel raro 1.1-1.3 cm. longus, lobis ovatolanceolatis vel lanceolatis, apice acutis vel raro obtusis, extra dense vel moderate lepidotis, margine lepidotis, eceliatis. Corolla tubulosa, 2.3-3.8 cm. longa, 5-loba, rosea vel rubella, rubro-maculata vel immaculata, extra moderate vel sparsim lepidota vel elepidota. Stamina 10 inaequalia, 1.6-3 cm. longa, corollam aequantia vel breviores; filamenta dimidio inferiore dense pubescentia. Ovarium conoideum vel ovoideum, 2-4 mm. longum, 5-loculare, dense lepidotum; stylus longus gracilis rectus, corollam aequans vel superans, elepidotus, glaber. Capsula conoidea vel ovoidea, 5-7 mm. longa, 4-5 mm. lata, moderate vel dense lepidota, calycis lobis persistentibus circumcincta vel raro semi-occulta.

ASSAM. Manda La. Balipara Frontier. Rhododendron sp. Glaucum? A straggling lepidote shrub in the conifer-rhododendron forest. Leaves lepidote on both surfaces paler beneath but scarcely glaucous. Corolla fleshy, pink, lepidote. Truss 4-5 fl. K cut to the base, segments acute, not foliaceous. Style glabrous, excluded, longer than stamens; filaments hairy at base. 10,000-11,000ft. 19.5.35. Kingdon-Ward No. 11463 (Holotype in Herb. Brit. Mus.).

ASSAM HIMALAYA. Poshing La. On rocks and precipitous earth slopes. Flowers deep rose. 11,000 ft. 25.5.1938. F. Kingdon-Ward No. 13672

E. BHUTAN. Nyuksang La, Sakden. Shrubs 5-7 ft. Flower over. Seed collected. In open rhododendron forest. Altitude 10,500 ft. 15.11.1936. F. Ludlow & G. Sherriff No. 2856.

SOUTH EAST TIBET. Marmang. Nyam Jang Chu. Prostrate shrub 1 -2 ft. Corolla pink, spotted inside. Filaments pink. Calyx pale green. Growing on rocks beside waterfall. Altitude 10,000 ft. 23.5.1947. F. Ludlow, G. Sherriff, & H.H. Elliot No. 12535.

BHUTAN. Rudo La. (E. side). Shrub 1 ft.-2½ ft. Buds rose pink; corolla pink, lobes almost white, some darker spots inside; filaments white & with white hairs; style pink at base, green upper end; stigma green; anthers pale brown, calyx green, tinged pink; leaves aromatic; pale grey green below. Common on rock faces in rhododendron forest on E side of the pass only. Altitude 11,000-12,000ft. 18.5.1949. F. Ludlow, G. Sherriff, & J.H. Hicks No. 18887. E. BHUTAN. Lao. Trashi Yangsi Chu. Shrub 3 ft.-4 ft. Flowers deep rose pink at base of corolla shading to paler pink, white corolla lobes; calyx reddish green with scales; filaments white, ciliate to half way up with white hairs; anthers brown, ovary green; style naked, pink at base, shading paler; stigma green; pedicel pinkish green; glands, lamina underneath white indumentum, with red glands; flowers have faint aromatic scent. Growing in rhododendron & bamboo mixed forest. Altitude 9,000 ft. 9.5.1 949. F. Ludlow, G. Sherriff & J.H. Hicks No. 2061 3.

BHUTAN. Lao. Trashi Yangsi Chu. Shrub 4 ft.-5 ft. Flowers rose pink shading to white corolla lobes; crimson spots in corolla throat; calyx reddish green; filaments white; anthers brown; style bright rose, stigma green; lamina, white indumentum with dark crimson glands. Faint aromatic scent. Altitude 10,000 ft. 11.5. 1949. F. Ludlow, G. Sherriff, & J.H. Hicks No. 20623.

This plant was first described as R. glaucophyllum var. tubiforme . Further investigation of specimens and plants in cultivation shows that it merits specific status. It belongs to the Glaucophyllum Subseries, Glaucophyllum Series.

R. tubiforme was discovered by Kingdon-Ward in May 1935 at Manda La, Assam frontier. It was later found by him again at Poshing La, Assam. The plant was also collected by Ludlow and Sherriff, and together with Elliot or Hicks in east Bhutan and in south-east Tibet. It grows in conifer-rhododendron forests, in open rhododendron forests, in mixed rhododendron and bamboo forests, on rocks, and on precipitous slopes, at elevations of 2,745-3,660 m. (9,000-12,000 ft.). It is recorded as being common on rock faces in rhododendron forests in Bhutan.

The diagnostic features of this plant are the tubular corolla, 2.3-3.8 cm. in length, and the long, slender and straight style, as long as the corolla or longer. In these respects it is readily distinguished from R. glaucophyllum . It also differs in that it grows up to 7 feet high, whereas R. glaucophyllum reaches a height of 4 feet.

The species was introduced by Ludlow and Sherriff in 1936 from East Bhutan (No. 2856). In cultivation it is a broadly upright shrub, up to 5or6 feet high, well-filled with dark green foliage. It is fairly fast-growing, and provides an admirable display with its deep rose flowers produced freely in clusters of three to five. The plant is hardy, but to be able to grow it satisfactorily, particularly along the east coast and in gardens inland, a well-sheltered position should be provided.

A broadly upright shrub, 30 cm.-2.14 m. (1-7 ft.) high; stem and branches with smooth, brown, flaking bark; branchlets rather densely or moderately scaly. Leaves evergreen, obovate, oblong-obovate, oblong, lanceolate or oblanceolate, aromatic, lamina coriaceous, 3.2-6 cm. long, 1.3-2.5 cm. broad, apex rounded, obtuse or acute, mucronate, base obtuse, tapered or rounded; upper surface dark green, shining, rather densely or moderately scaly; under surface markedly glaucous, densely scaly, the smaller pale yellow scales 1-2 times or sometimes 3 (or rarely 4) times their own diameter apart, the larger dark brown scales closely or widely separated; petiole 0.4-1 cm. long, rather densely or moderately scaly, glabrous. Inflorescence terminal, or rarely terminal and axillary in the uppermost one or two leaves, umbellate or shortly racemose, 3-5-flow-ered; rhachis 2-3 mm. long, scaly or not scaly; pedicel 0.8-1.6 cm. long, shorter than the corolla, rather densely scaly. Calyx 5-lobed, leafy, 5-8 mm. or rarely 1.1-1.3 cm. long, lobes ovate-lanceolate or lanceolate, apex markedly pointed or rarely obtuse, outside rather densely or moderately scaly, margin scaly, not ciliate. Corolla tubular, 2.3-3.8 cm. long, 5-lobed, pink, deep rose, or pink with white lobes, with or without darker spots, outside moderately or sparsely scaly or not scaly. Stamens 10, unequal, 1.6-3 cm. long, as long as the corolla or a little shorter; filaments densely hairy in the lower half. Ovary conoid or ovoid, 2-4 mm. long, 5-celled, densely scaly; style long, slender, straight, longer than, or as long as, the corolla, not scaly, glabrous. Capsule conoid or ovoid, 5-7 mm. long, 4-5 mm. broad, moderately or rather densely scaly, enclosed or rarely partly enclosed by the persistent calyx-lobes.

Rhododendron cinnabarinum Hook, f. var. breviforme Davidian var. nov.

R. cinnabaríno Hook. f. similis sed corolla breviore tubulosa 3-3.2 cm. longa, extra rutila intus lutea differt.

N. E. BHUTAN. Lao, Lao Chu. Identifying specimen for seed of rhododendron. Situation, mixed rhododendron & Abies forest. R. cinnabarinum forma. F. Ludlow, G. Sherriff, and J. H. Hicks No. 21283 (Holotype in Herb. Brit. Mus. Details of the flower are taken from a cultivated plant).

Ludlow, Sheriff and Hicks discovered this plant in fruit under No. 21283 in October 1949, at Lao, Lao Chu, north-east Bhutan, growing in mixed rhododendron and Abies forest at an elevation of 3,173 m. (10,500 ft.). They introduced it in the same year.

This variety is readily distinguished by the short tubular corolla, 3-3.2 cm. long, bright red outside, deep yellowish inside and at the margin of the lobes.

In cultivation, the plant has been known as R. cinnabarinum "var Nepal". It is a broadly upright shrub, somewhat compact, up to 1.22 m. (4 ft.) or 1.53 m. (5 ft.) high, densely filled with foliage. The plant is free-flowering and should be included in every collection of rhododendrons. It received an Award of Merit when exhibited by Hydon Nurseries Ltd. Surrey, in 1977 (L. S. & H. No. 21 283 — the Type number).

Rhododendron glaucophyllum Rehder var. album Davidian, var. nov.

Aspectu R. glaucophylli Rehder sed corolla alba, plerumque minore ad 2 cm. longa recedens.

NEPAL. Barun Khola. On rocky banks. Erect and woody at a height of 1 m. In the open and well drained. 10,000 ft. 25.11.1971. L. W. Beer,C. R. Lancaster, D. Morris No. 12319 (Holotype in Herb. Brit. Mus. Details of the flower are taken from a cultivated plant).

This plant was first collected by Beer, Lancaster, and Morris in November 1971 at Barun Khola, Nepal (No. 1 231 9). It grows on rocky banks, in the open well drained localities, at an elevation of 3,050m. (10,000ft.).

The variety differs from the species in that the flowers are white, usually smaller, up to 2 cm. long.

The plant was introduced by Beer, Lancaster, and Morris under seed No. 31 5 (= 12319). In its native home it is an erect shrub, 3 feet high; in cultivation it is somewhat compact spreading up to 1½ feet high and is likely to grow taller. It is hardy and free-flowering. A form was named 'Len Beer' when exhibited in 1977.

Rhododendron lepidotum Wall , ex G. Don var. album Davidian, var. nov.

Aspectu R. lepidoti Wall, ex G. Don sed corolla alba vel albida, ad 1.5 cm. longa, foliis lanceolatis vel oblanceolatis ad 2.5 cm. longis recedens.

NEPAL. Mauey Dara Flowers white. Alt. 13-14,000 ft. 1930. Major Lall Dhevoj No. 510.

BHUTAN. Gya Sa Dzong. Mo Chu. Calyx green; corolla white, slightly tinged pink on outside of several petals; creamy filaments, brown anthers; style pinkish white, stigma green. Shrub 1 ft.-2 ft. growing on open grassy banks. Altitude 9,000 ft. 12.6.1949. F. Ludlow, G. Sherriff, & J. H. Hicks No. 16510.

BHUTAN. Tobrang. (Trashi Yangse Chu). Flowers white. In crevice in a small cliff. Altitude 7,500 ft. 7.7.1 949. F. Ludlow, G. Sherriff, & J. H. Hicks No. 20900 (Holotype in Herb. Brit. Mus.).

NEPAL. 1961. Col. Spring Smyth No. 51.

This plant was first found by Major Lall Dhevoj in 1930 in Nepal. It was later collected by Ludlow, Sherriff and Hicks in Bhutan in 1949, and by Col. Spring Smyth in Nepal in 1961. It grows on open grassy banks and in crevices of cliffs at elevations of 2,288-4,270m. (7,500-14,000ft.).

The variety differs from the species in that the corolla is white or white slightly tinged pink. It is a small, broadly upright or spreading shrub, 30-60 cm. (1-2 ft.) high. The leaves are evergreen, lanceolate or oblanceolate, up to 2.5 cm. long, and the corolla is up to 1.5 cm. long.

It was introduced into cultivation by Col. Spring Smyth in 1961 from Nepal (No. 51).

Rhododendron lepidotum Wall, ex G. Don var. minutiforme Davidian, var. nov.

Aspectu R. lepidoti Wall, ex G. Don sed corolla minuta 5-9 mm. longa, foliis deciduis minimis lamina 3-7 mm. longa 2-4 mm. lata differt.

NEPAL. Brought from Gosainthan, Khatmandu, August 1927. Flowers very numerous, small 5 petalled, the colour of the Bougainvillea and with a sweet attar-like smell. A bush-like plant somewhat resembling the Bog Myrtle. Found at Tare. Grows in sunny damp places covering the ground. Lakshman Mali No. 14. Khibolsuba.

NEPAL. Above Ranmagaon. Dwarf shrub on ridge to 3 ft. Flowers deep magenta. Leaves scaly above and below. Alt. 12,000 ft. 2.7.1954. Stainton, Sykes & Williams No. 3353.

NEPAL. Rambrong, Lamjung Him-al. On top of large boulders. Shrub of 1 ft. Corolla dull red. Alt. 13,000 ft. 6.7.1954. Stainton, Sykes & Williams No. 6190 (Holotype in Herb. Brit. Mus.).

NEPAL. 1961. Col. Spring Smyth No. 35.

This plant was first collected by Lakshman Mali in 1927 in Nepal. It was afterwards found by Stainton, Sykes and Williams in 1954 and by Col. Spring Smyth in 1961 in the same region. It grows in damp places and on boulders at an elevation of 3,965 m. (13,000ft.).

The variety is distinguished by the minute corolla, 5-9 mm. long, red or crimson-purple. The leaves are deciduous, tiny, laminae 3-7 mm. long, 2-4 mm. broad. It is a small, rounded compact, or broadly upright shrub, 30-60cm. (1-2 ft.) high.

The plant has long been in cultivation. It was reintroduced by Col. Spring Smyth in 1961 (No. 35).