Rhododendron atlanticum (Ashe) Rehd.

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Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Rhododendron atlanticum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-atlanticum/). Accessed 2020-01-20.

Genus

Synonyms

  • Azalea atlantica Ashe

Other species in genus

Glossary

calyx
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
corolla
The inner whorl of the perianth. Composed of free or united petals often showy.
ovary
Lowest part of the carpel containing the ovules; later developing into the fruit.
acute
Sharply pointed.
apex
(pl. apices) Tip. apical At the apex.
appressed
Lying flat against an object.
article
(in Casuarinaceae) Portion of branchlet between each whorl of leaves.
ciliate
Fringed with long hairs.
clone
Organism arising via vegetative or asexual reproduction.
cuneate
Wedge-shaped.
glabrous
Lacking hairs smooth. glabrescent Becoming hairless.
glandular
Bearing glands.
glaucous
Grey-blue often from superficial layer of wax (bloom).
indumentum
A covering of hairs or scales.
introgression
Incorporation of genes from one species into the genotype of another through repeated hybridisation or repetitive backcrossing between a hybrid and one of its parents.
midrib
midveinCentral and principal vein in a leaf.
style
Generally an elongated structure arising from the ovary bearing the stigma at its tip.

References

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Rhododendron atlanticum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-atlanticum/). Accessed 2020-01-20.

Deciduous shrub, 1(-3) m; strongly rhizomatous; young twigs covered in a mixture of eglandular and glandular hairs. Leaves ovate or obovate to elliptic, 3.2-5.2 x 0.8-2 cm usually glabrous, lower surface pale to glaucous, with eglandular and/or gland-tipped hairs. Flower bud scales glabrous or covered with unicellular hairs, margin unicellular-ciliate. Pedicels covered gland-tipped or eglandular hairs. Flowers with a sweet musky fragrance, appearing before or with the leaves, 4-13, in a shortened raceme; calyx 1-3(-10) mm; corolla white to pale pink, funnelform, tube gradually expanding into limb, outer surface covered with eglandular and gland-tipped hairs, 25-50 mm. Capsules covered with unicellular and multicellular gland-tipped hairs. Flowering April-May. Royal Horticultural Society (1997)

Distribution  United States Eastern Coastal Plain

Habitat s.l.-150 m

RHS Hardiness Rating H6

Awards AM 1964 (Crown Estate Commissioners, Windsor) to a clone 'Seaboard'; flowers white, with pale pink corolla tube.

Conservation status Least concern (LC)

Taxonomic note R. atlanticum is allied to R. viscosum and R. arborescens. It is distinguished from both by the flowers appearing before the leaves and from the former by its generally less dense indumentum. Royal Horticultural Society (1997)

A deciduous, stoloniferous shrub up to 3 ft high; young shoots glabrous apart from scattered appressed hairs and occasional glandular hairs. Leaves obovate to oblong-obovate, rounded to subacute at the apex, cuneate at the base, light green or bluish green above, green or slightly glaucous beneath, usually glabrous on both surfaces apart from the slightly hairy midrib. Flowers fragrant, borne in May with or slightly before the leaves in clusters of four to ten, very fragrant, on hairy pedicels up to 12 in. long. Calyx up to 16 in. long, glandular-ciliate. Corolla white, flushed with pink outside, tubular-funnel-shaped, the tube glandular, 1 to 112 in. long, rather gradually widening to the limb, which is 114 to 112 in. across; lobes acute, each with a line of stalked glands along the midrib outside. Stamens about twice as long as the tube. Ovary clad with bristly, sometimes gland-tipped, hairs; style longer than the stamens. (s. Azalea ss. Luteum)

Native of the eastern USA in the coastal plain from Delaware to South Carolina; introduced to Britain in 1922. ‘In late April and early May the Coast azalea makes a truly splendid sight as a multi-hued understory to the open pine woods of the coastal Carolinas. Since it is highly stoloniferous it recovers promptly in the wake of a brush fire or roadside trimming or grazing, so that the year following will again see hundreds of upright flower clusters on wiry, knee-high stems borne by one plant an acre or more in extent’ (H. T. Skinner, R.C.Y.B. 1957, p. 13). In this article, Dr Skinner suggests that typical R. atlanticum, described mainly from plants growing in Virginia and the Carolinas, may be the result of introgression of genes from R. canescens and R. nudiflorum, and that the original form of the species, uncontaminated by hybridisation, is represented by plants found in Delaware, which are white-flowered and far more glandular than typical R. atlanticum.

R. atlanticum is an azalea of great charm, very hardy and growing vigorously in moist soil. But flowering as it does at the peak of the rhododendron season it will go unnoticed unless planted well away from its more flamboyant rivals. It associates well with low-growing herbaceous plants.

The Award of Merit was given on May 25, 1964 to the clone ‘Seaboard’, exhibited by the Crown Estate Commissioners, Windsor Great Park.


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