QBARS - v33n1 Winter Foliage of Rhododendrons

Winter Foliage Of Rhododendrons
Bob Badger Kent, WA.

The enormous impact of rhododendrons on the planning and arrangement of gardens here and in Europe has been concentrated in the short time of just 50 or 60 years, since the tremendous collections of rhododendron species in Asia by Wilson, Forrest, Kingdon-Ward, J. F. Rock and others. The flood of new species gave rise to a secondary swarm of new hybrids which has continued unabated, until the present.

The glorious floral displays of rhododendrons fill the gardens from March until July with such beauty and colors that it literally defies description. Flowers in shades of whites, pinks, reds, yellows, blues and purples.

Flowers, individually from one quarter of an inch to nearly seven inches in diameter borne singly and in many arrangements up to great umbels of twelve to fourteen inches in diameter.

And the evergreen leaves in many sizes from three eighths inch long to two feet and more. The garden importance of evergreen rhododendrons is one of solidarity out of bloom, and riots of color tones when in bloom. To this I all agree. But, I wish to draw your attention to their "Winter Color". Not the color of flowers. I refer to the winter color of their evergreen foliage.

The most exotic of winter foliage color changes occurs among the Asian rhododendron species. Some fine color changes also occur in first and second generation hybrids thereof, but the species are the prize winners.

Nearly all lepidote (scaly-leaved) rhododendrons change their leaf color after the first hard frosts of fall. Some changes are most vivid. The greens of summer are replaced by purple, bronzy-red and maroon tones for winter. Perhaps you never noticed this before.

Take heed of the following list so that you may plant the dwarfest or "little people" sorts in elevated positions above walls or in rockeries so you will not have to kneel on the wet soil to appreciate their winter beauty. The medium, "people-sized" plants, should be planted on a more level area where you can "shake hands" with them in winter. And lastly the tallest growing sorts with the brilliant under leaf colors should always be sited uphill on slopes above the grass or path, or on the upper terrace so that the fine colors beneath their leaves can be more easily seen as you walk by on a winter's day.

One bright day this December almost on the Winter Solstice, I visited the Rhododendron Species Foundation Garden at Federal Way. With the kind assistance of the staff and President, I wandered through the magnificent Study Garden area of related species plants. Here are my notes of the eighty finest of the winter foliage colorations that I saw that day. I rated their "Winter Color" on the following basis: (A) Overall appearance of the winter leaf color: (B) Shining, glossy or matte look of the upper leaf; (C) Brilliance of the under leaf color tones whether the color comes from scales or hairs; (D) Vividness of the color of this year's growth; (E) Color of the bark; (F) Bright color tones of the growth and flower buds and (G) Remarkable colors on the petioles of the leaf.

RATINGS:
WC-0 I passed it by
WC= Above average leaf and other color changes, a winter attraction in anyone's garden.
WC-** Remarkable color changes in leaf upper surface. Also other attributes in color from stems, or underleaf or petioles or buds. Plant to see.
WC-*** Absolutely Choice, a must have for winter gardens. A colorful plant in bloom or out, but an asset especially in the winter months. Plant in a place of honor.

WC-* dasypetalum , bronze tones above over greens with buff colors on the under leaf
WC-** impeditum , a mound of gray green leaf tones above, suffused here and there with light and medium blue colors - especially on the last growths of summer. Flower buds tinted with fawn and maroon colors. Under leaf, pale grey-green.
WC-** fastigiatum , also a tight mound but more gray-blue in coloration with bright flashes of blue. Under leaf is a soft mushroom color.
WC-*' polycladum , (old name was scintillans ) a more upright grower covered with matte-green leaf tones, with noticeable maroon colored flower buds cupped in the terminals. Gray-brown beneath.
WC-* nivale , subspecies boreale (old names were violaceum and stictophyllum ) larger cushions of matte soft gray-green colors overlaid with grayed-maroon shades. Leaves rufous colored beneath.
WC-** nivale , subspecies nivale (old name was paludosum ) larger cushions of soft olive-green colors above with contrasting bright red flower buds on the terminals. Under leaf yellowish to fawn in color.
WC= flavidum var. flavidum (old name was flavidum ) a rather erect and taller growing shrub with somewhat glossy medium green leaves. Pink flower buds rest on the upright terminals. Under leaf surface is grayed-green in color.
WC-* rupicola var. rupicola (old name was rupicola ) a low mound of variable tones ranging from darker olive green tones to richer bronzy highlights. Flower buds are rather pink in color. Under surface of the leaves are fawn to rust in coloration.
WC-** russatum , a taller, full shrub with aromatic leaves. Leaves are olive-green and darker with the growth points studded with soft maroon colored flower buds. Leaf undersurface is brownish-rusty in color. This year's growth stems are a distinct maroon color.
WC-** cuneatum , a tall but looser-growing shrub with gray-green leaves above that are dark fawn to darker rusty beneath. The bigger leaves are thinner in texture and when lighted by the sun and viewed from the other side, the leaves have an almost iridescent olive color that is quite interesting.
WC-* rupicola var. chryseum (old name was chryseum ) a low mound with olive-green leaves having highlights of bronze and maroon. Pinkish toned flower buds set amongst the leaves. Under leaf rust and fawn colored.
WC-* hippophaeoides var. hippophaeoides , (old name was hippophaeoides ) an erect and spreading shrub with matte leaves of a distinct grayed green-blue color. Buds are variable in maroon and reddish colors. The under leaf is a brighter yellowish-buff color often seen if the wind flutters the leaves. Stems of the new growth are of a fawn-yellow color.
WC-** telmateium (old name was idoneum ) a low shrub with leaves somber matte gray-green above but with golden colors beneath. The new growth stems are also a rich golden color in contrast to the leaves. Very striking winter effect.
WC-* orthocladum var. microleucum (old name was microleucum ) a much-branched cushion that has leaves of dark olive and lighter green colors flashed here and there with yellow-greens. The flower buds are of the same colors. Leaf undersurface is fawn-colored.
WC-* intricatum , a compact, tangled and intricately branched shrub whose leaves are various shades of yellowish-green to olive tones above. Under leaf is buff to straw colored.
WC-* keleticum , a vigorous low cushion of a shrub with outer branches almost creeping. The small leaves turn a burnished, shining dark purple-maroon with greener leaves interspersed. The bright maroon-red petioles are very noticeable.
WC-** radicans , a creeping mat former with glossy leaves of rich green tones here and there, changing to lustrous bronzy and maroon tones. The tiniest of the "little people".
WC-* prostratum , an almost prostrate shrublet with shining bright green leaves. Flushed bronzy on some leaves and with orange-red young stems.
WC-** chameunum , a mounded shrub, more upright, covered with lustrous bright maroon-red leaves. Stems of new growth the same bright maroon-red.
WC-** calostrotum , an upright twiggy shrub. Leaves of the first growth are a matte gray-maroon above but they stand up exposing pinkish-tan color beneath. In contrast, the leaves of the second growth are a brilliant blue-green.
WC-* campylogynum , the various forms are rich dark green in leaf color with the more exposed leaves brushed with maroon colors. Petioles are often bright yellow-green.
WC-* linearifolium , this upright evergreen azalea species or variety has long narrow dimorphic leaves in the winter, resembling lacy purple fluffs on the branch tips. Very unusual effect.
WC-* yakuinsulare , an evergreen azalea best described as a low mounder. The tiny, narrow leaves are of a bright, somewhat shining bronzy color. Very restrained in feeling.
WC-** sataense , this upright evergreen azalea inhabitant of volcanic peaks of Kyushu, sparkles with bright red, rusty-maroon and vivid yellow-green leaves, interspersed at random over the plant. A brilliant display of color in the winter garden.
WC-* serpyllifolium , another evergreen azalea with a wide spreading wide flat habit, smothered in tiny one-half inch leaves of a rich maroon color.
WC-* nakaharai, this evergreen species is the prostrate carpeter of the azaleas. Its narrow leaves are crisp light blue-green, with bronzy flashes. The leaves are covered above with long white hairs while the buds are clothed in hairs of brightest gold.
WC-* kaempferi , tall evergreen azalea species whose leaves are of various shades of maroon, green and orange-red, it has buds covered with rather red bud scales.
WC-* keiskei , The tall upright forms have long yellow-green and bronzy leaves with pale maroon buds. - the lower mounding forms, are smothered in rich maroon leaves that are green beneath. The buds are of the same maroon tone. var. cordifolia , is the spreading prostrate form from elevations near a mile high. Its leaves are of maroon, yellow and green tones while the buds are similar.
WC-* pemakoense , a low, spreading mounder covered with dark green leaves above. Very striking in winter, because every flower bud is colored a bright red.
WC-* patulum , this shrublet has leaves of maroon-red tones that are soft gray-green below. The bud scales are of a brighter red hue.
WC-* imperator , another shrublet of green and bronzy leaves, edged deeper maroon as are the petioles.
WC-* leucaspis , a low bushy shrub that has matte-green furry leaves set with buds of pinkish-red.
WC-** hanceanum (and var. nanum ) have leaves of medium green occasionally brushed in bronzy tones. However, the buds and petioles are of a bright red-maroon color. Some forms are covered in leaves of bright maroon. Very attractive when well grown.
WC-* dauricum , the type is a twiggy upright shrub whose leaves are russet-bronze all over above and coppery-buff below - the leaves of the white-flowered form never color in winter. They remain a bright yellow green as do the buds - a dwarfer sort of regular color has leaves that turn a rich russet color all over.
WC-*** sulfureum , an upright shrub with bright soft green leaves. It is very ornamental on a dull winter day because, cupped in each terminal leaf cluster, is a flower bud of a brilliant red color. The edge of each bud scale is traced with pure white. A choice plant to be placed where it can be easily viewed in the winter.
WC-* spinuliferum , a sprawling, larger shrub with longer leaves of a green fuzzy-matte appearance. The three inch or so long leaves are almost always edged around with a richer maroon color.
WC-* baileyi , a scraggy, upright shrub with leaves of gray-green or gray-russet colors. Not that attractive except that every flower bud is of an unusual pinkish color that contrasts with the leaves.
WC-* lepidostylum , a spreading, low shrub of compact habit whose leaves, the most brilliant blue of the genus in summer, turn to duller shades of gray-green and maroon in the winter.
WC-* crassum , a big shrub which is the hardiest of the large-flowered Maddenii's. The crisp, veined leaves are of an olive-green color above. But when caught by the wind the undersides are of a shining greenish-gold color.
WC-** moupinense , a spreading lower shrub with bright yellow-green leaves. Each flower bud is a contrasting bright red-maroon.
WC-** racemosum , an upright twiggy shrub with medium green to grayish leaves with pink and gray flower buds. Its outstanding feature on the best forms is that last year's new growth stems are a bright attractive red.
WC-* davidsonianum , a taller upright shrub with medium green leaves and green-gold buds. The better forms have red stems.
WC-** rigidum , another taller shrub whose finer forms are most attractive. The stems are a bright plum-purple color and are decorated with smallish blue-green leaves. The effect is very different - somewhat like oreotrephes - and I feel this plant should be planted along an entry walk for fine winter color effect.
WC-*** zaleucum , an upright taller shrub that presents a superb winter color effect for landscaping uses. The bright walnut-brown stems bear many long very dark green leaves that flutter in the stronger winds, exposing their ghostly, glaucous-white undersurfaces. And as if that was not enough, the flower buds are covered with scales of a bright golden-yellow hue. A very choice selection for your garden.
WC-** oreotrephes , an upright growing shrub with decided glaucous blue-green almost round leaves. Some forms are semi-deciduous, but the best forms are not. These better forms have maroon to purple to violet stems which are very noticeable in the winter.
WC-* williamsianum , a low spreading shrub with smaller rounded, dark green leaves that are alight greeny-white below. The winter buds are a bright red-maroon in contrast to the leaves.
WC-** beanianum , a low shrub with somewhat shining oblong, very dark green leaves, somewhat crinkled on the edges. The leaf petioles and stems are a contrasting reddish color and are covered with bristly greeny-brown hairs. The reddish-brown woolly indumentum appears rich brown when the sun shines "through" and one sees the leaf from below.
WC-* tsariense , a smaller rounded shrub with a woolly fawn colored indumentum often persisting on top of the last leaves of the new growth. The smallish obovate leaves are of a medium green color. The stems, petioles and buds, are of a golden-yellow tone that hints of orange in certain lights. A plant to be seen by all.
WC-* recurvoides , a low compact shrub with somewhat narrow dark green leaves that are shining above. The young shoots are of a dark maroon color and like the leaf petioles, are covered with olive-brown bristles. The indumentum beneath is thick and spongy and of a rich olive tone which contrasts with the bare yellow-white midrib. Plant it on the up slope above a walk.
WC-** hyperythrum , a low shrub with quilted, medium-green leaves with a thin-lined, bright yellow midrib above. The petiole is red in contrast to the green leaves. The bud scales are in shades of red and green also. Altogether, the winter colors are intriguingly unusual, if not bizarre. It should be planted where it can be easily seen - anytime visitors walk by.
WC-* yakushimanum , a low, compact, mounded shrub with dark green recurved leaves with a yellow-green midrib. The petioles and buds are covered with a soft white or gray tomentum. At times a white tomentum remains on the uppermost leaves of the growth, adding to the character of the plant.
WC-** succothii , a medium sized shrub with blued-green oblong leaves that are distinctly "eared" (cordate leaves). The leaf petioles are so short that the leaves cluster on the branch ends. An unusual effect.
WC-* pseudochrysanthum , the dwarfer forms have somewhat pointed leaves held up at an angle. The medium-green leaves are often covered with a white meal-like tomentum. The growth shoots, petioles, flower and growth buds are of a red or maroon color. The leaves are frequently red or maroon underneath. The effect is somewhat artificial but striking.
WC-* brachycarpum , a medium sized, rounded shrub with larger dark green somewhat recurved leaves. The midrib, petiole, and buds are of a distinct yellow color which contrasts vividly with the dark leaves. A pleasing garden effect.
WC-** makinoi , a medium sized, rounded shrub with long, narrow, recurved green leaves. The petioles are covered with a gray tomentum while the terminal buds are a soft brown. The total effect is very unusual, but pleasing.
WC-* oreodoxa , on this rounded larger shrub, the medium green leaves hang downward sometimes rather recurved. Contrasting with the green leaves are the buds, petioles and leaf midrib, all of which are a yellow-green color. Effective in the background.
WC-* fargesii , a large shrub which on the richer colored flower forms, have thicker elliptic leaves with rather a reddish-purple petiole borne on stems reddened toward the tips. A noticeable effect in winter.
WC-* insigne , a medium shrub having the same garden effect as brachycarpum, that is to say, green leaves with yellow midribs and petioles. In one form the leaf also has a yellow edge. The indumentum beneath, has a coppery-pink color when viewed from the side or below.
WC-** campanulatum var. aeruginosum , a medium sized shrub that has blue toned green leaves, recurved at the edges. The indumentum beneath when visible is of a soft reddish-yellow color. The petioles, buds and new growth are of a bright red color for contrast. Most attractive and colorful in winter.
WC-* campanulatum , is a larger shrub, somewhat loose in habit with larger oval leaves of a medium green with purple petioles and new growth stems. Leaves of larger plants frequently flutter in the winter wind exposing their brownish-red felted undersides.
WC-** orbiculare , a medium-sized rounded shrub with medium green rounded leaves having "ears" which overlap the petiole from each side. The undersides are palest green-white. The petioles are of a pinkish-red color. The growth and flower buds are decorated with long pale yellow-green bracts which project upwards like clusters of fingers. A very pleasing plant to view in winter.
WC-*** fulvum , a large shrub bearing darkest green leaves a little rolled on the edges. The midrib and veins above are pronounced lines of yellow-green against the dark green. Buds are furred in a soft orange tomentum. The plant usually holds its leaves somewhat upright, exposing the most vivid, vibrant orange indumentum in the genus. This is perhaps the most brilliantly indumented and finest of winter colored shrubs for the garden. Plant for everyone to see and for you to see from your own windows in the winter!
WC-** bureavii , a medium sized full shrub with dark green leaves, somewhat shining above as the tomentum falls away. The leaves nestle tightly against the shoots, seldom exposing the beautiful thick, woolly rusty indumentum beneath.
WC-*** Sir Charles Lemon, this "honorary species," Is a larger upright shrub bearing dark green leaves which are covered beneath with a red-orange indumentum which is seen every time the wind blows. The new growth, the petioles and the buds are all of a rich maroon-red color. A striking plant if placed where it can be easily seen.
WC-* mallotum , a stout-branched, medium sized shrub bearing stiff, oval, dark green rumpled leaves with a bright yellow midrib above. The leaf petioles, new growth stems, and buds are clothed with a greenish-gray tight indumentum. Beneath, the leaves are covered with a rich orangey-brown indumentum.
WC-** fictolacteum , this shapely well branched small tree, is abundantly covered with large dark green leaves. The leaf petioles are usually a gray-buff in color, while the undersides are clothed in an orange-brown indumentum which is easily seen as you look up into the plant. To be placed and grown as a dominant small tree in your landscape. Hardy!
WC-* arizelum , another shapely, small tree which is hardy. Large, obovate dark green rough surfaced leaves clothe the plant. The petioles and new shoots are coated with a grayed cinnamon colored indumentum. The leaf undersides are clothed with a rich cinnamon-brown indumentum. A tree in the landscape.
WC-* calophytum , a stout-branched very hardy tree bearing long narrow leaves up to fifteen inches long. The medium green leaves are paler green below. In some forms the leaf petioles are of a reddened tone while in others they are of the same green as the leaves. The winter garden effect is that of a powerful massive, dominating evergreen tree.
WC-* eximium , a small tree with oval leaves up to twelve inches long. The rugulose (rough surfaced) leaves are dark green ultimately but are often covered, as are the petioles and new shoots, for a year or more with a thick rusty-cinnamon colored tomentum. Beneath, the leaves are covered with a thick indumentum of a rusty-orange color. A very attractive small tree that "shows off" its leaves all year long. Plant it in a more protected position - but where it can be seen.
WC-* falconeri , a fairly large, stout branched tree bearing rather large rough surfaced very dark green leaves. The midribs above are of a bright contrasting yellow color. The leaf is covered below with a dense indumentum which is of a rusty-orange color. Very striking in larger plants. It is somewhat tender and should be placed in a protected area, but situated to be easily seen for its winter effect.
Well that's the way I rate the species "Winter Color" here in our Puget Sound climate of Washington State. My personal top ten list for "Winter Color" effect is:

"Little People"
R. radicans
R. calostrotum
R. russatum

"People-sized Plants"
R. zaleucum
R. rigidum
R. sulfereum
R. sataense
R. hyperythrum

"Big Fellows "
R. fulvum
R. eximeum

Now its up to you to make up your list.