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Journal American Rhododendron Society

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Dr. Glen Jamieson ars.editor@gmail.com


Volume 60, Number 4
Fall 2006

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The Ericaceae of the Pacific Northwest, Part III
Wilbur L. Bluhm
Salem, Oregon

        Two subspecies of Cassiope mertensiana, ssp. gracilis, Piper's Mountain Heather, and ssp. mertensiana, White Mountain Heather, are in the Pacific Northwest. Piper's Mountain Heather is at high elevations east of the Cascade Mountains, in Oregon in the Wallowa Mountains and into Idaho and Montana. White Mountain Heather is in the central Cascade Mountains of Oregon northerly to Alaska and south into northern California, where it may be a different subspecies.
        Cassiope mertensiana is a subalpine to alpine plant, not often below timberline. It likes moist slopes, moist areas around rocks, and areas of late snow melt.
        These Mountain Heathers are low shrubs, 2 to 12 inches high, that form wide spreading mats. The less than inch long sessile leaves are opposite and 4-ranked, making the stem look almost square. They are closely appressed and overlapping to almost conceal the stem, and have papery margins. The leaves give the plants a dark green appearance. The foliage resembles that of Scottish Heather, Calluna vulgaris.
        The to ⅓ inch wide bell-shaped white flowers are 5-lobed and are showy against the dark foliage. The 3 to 5 clustered flowers are at the stem ends. A near globose capsule follows flowering.
        Their attractiveness makes Mountain Heathers tempting rock garden plants. They are not easy out of their element in lower elevation gardens. Dr. Arthur Kruckeberg suggests a cool nook in a rockery or in a peaty, gritty raised bed in sun, but with damp soil, for them to do their best.

C. tetragona var. saximontana, Four Angled Mountain Heather, closely resembles the preceding species. Differences are minor, such as the distinct groove on underside of leaves and red sepals of Four Angled Mountain Heather, plus a few other technical differences.
        Four Angled Mountain Heather is a circumboreal species, alpine in British Columbia, Washington, and Rocky Mountains. Much of the discussion of C. mertensiana is applicable to this species.

C. lycopodioides, Clubmoss Mountain Heather, differs from the two previous species in having leaves not arranged in four distinct rows. Unlike C. mertensiana, Clubmoss Mountain Heather's leaves do not have papery margins. In other respects it is similar to the other two.
        Range of Clubmoss Mountain Heather is from Alaska to Washington. It is typically a high mountain plant in the Cascade Mountains; however, near Seattle it occurs as low as 2000 feet.

Chimaphila menziesii, Little Prince's Pine, is a small, to 8 inches tall, evergreen woody perennial growing in coniferous woods from British Columbia south to southern California. Leathery leaves are dark green upper surface, lighter on lower, to 2⅓ inches long, elliptic and narrow, sharply toothed or toothless, and glabrous. From one to three nodding white or pink flowers are at top of a long stem. The 5 petals, each up to inch long, make a wide open face, fully exposing the relatively large pistil and stamens.
        It's a "cute" little plant in flower, tempting to the collector. However, it is nearly impossible to keep alive under cultivation and should stay in the wild.

C. umbellata var. occidentalis, Prince's Pine, Pipsissewa, is a larger version of C. menziesii, growing up to about a foot high. It has more and larger bright green leaves, to 2 inches long and inch wide, toothed toward end, and glabrous. Flowers are like C. menziesii except more, 3 to 10 per stem, and a little larger. Neither should it be collected, but allowed to stay where it naturally belongs.
        Prince's Pine, or Pipsissewa, has wide distribution, from Alaska to southern California to eastern North America, Central America, and Eurasia. In Pacific Northwest it grows in woods, especially under conifers.

Cladothamnus pyroliflorus, Copper Bush, is found from northwest Oregon to Alaska in moist forests, along stream banks, and edge of bogs. This deciduous shrub grows 1 to 10 feet tall. Nearly sessile leaves are light green and very thin, to 2 inches long. The flat open, coppery-pink flowers, about an inch wide, give Copper Bush its name. The style is recurved. Slow to establish, Copper Bush is a nice plant in a moist, acid soil.
        It may, in the future, be reclassified as a rhododendron. If so, the botanical name of the reclassified Cladothamnus pyroliflorus is not yet known.

Northwest Gaultheria species are a size-diverse group of plants, from an inch (G. humifusa) to nearly 6 feet (G. shallon). The leathery evergreen leaves range from inch (G. hispidula) to 2 to 4 inches (G. shallon). All bear white to pinkish flowers, more or less cup-shaped and flaring open at top in all but G. shallon whose flowers are urn-shaped. All have flowers with 5 petals and sepals, except G. hispidula which has 4 of each. The fruits of all are fleshy capsules or pseudo-berries.

G. hispidula, Moxie Plum, Maidenhair Berry, or Creeping Snowberry, grows as a spreading or trailing plant in sphagnum bogs or deep conifer woods from British Columbia south to northern Washington and northern Idaho, east to Labrador. It is covered with brownish-bristly appressed hairs. Small leaves are ovate (egg-shaped), revolute, and abundant. The small, to inch long, berries are white, juicy with mild wintergreen flavor. It's said to be one of most beautiful of tiny, creeping groundcovers for wet, acid area of the garden.

G. humifusa, Alpine, or Matted, Wintergreen, is a usually prostrate little shrublet hardly more than an inch high, with trailing, glabrous or finely hairy, stems. It's an alpine or subalpine plant in moist or wet meadows from British Columbia to northern California and east to Rocky Mountains. Leaves are ovate, oval, or nearly elliptic to an inch long, and half to two thirds as wide. Tiny flowers are less than inch, single in leaf axils. Small fruits are red, about inch broad. It's difficult to establish in the garden, but may be worth trying in a moist peaty site under conifers.

G. ovatifolia, Slender, or Oregon, Wintergreen, larger than the two preceding species, is a spreading shrublet, forming mats, to more than an inch high. Its stems have copious loosely spreading brownish hairs. Leaves are medium to deep green, shiny, ovate, pointed, to 1 inches long and almost as wide, with thick toothed margins. Flowers are single in leaf axils, the corolla twice as long as sepals. The relatively long, reddish hairs on calyx of Slender Wintergreen distinguishes it from Alpine Wintergreen. Berries of Slender Wintergreen are bright red, to ⅓ inch broad. Garden merit of this attractive plant is similar to Alpine Wintergreen. In the wild, it grows in fairly dry to moist coniferous forests to subalpine bogs, from British Columbia south in Cascade and Olympic Mountains to northern California, east to Idaho.

G. shallon, Salal, is the "workhorse" of these gaultherias. It is one of most useful Northwest native shrubs, either as a tall groundcover, in groups, or as individual plants. It is especially effective in massed plantings under conifers and other trees, or under large rhododendrons or other large shrubs. With moisture it can be used in full sun. It has great versatility in a large or small garden. The handsome leaves are widely used in the floral trade.
        Salal can grow to 6 feet or more. Its hairy stems grow from a few inches to 4 feet long. Leaves are ovate, nearly glabrous, deep green, shiny, sharply toothed, 2 to 4 inches long, 1 to 3 inches wide. Flowers and flower stems are hairy and glandular. Fruit is to ⅓ inch broad, glandular, hairy, nearly black, fleshy, and berry-like. The bland fruit was prized by coastal Native Americans, who gave it the name Salal. It is now used for preserves.
        Natural range of Salal is from British Columbia to southern California, mostly west of Cascade Mountains, from sea level to 2000 feet, more or less.

Harrimanella stelleriana, Alaska Mountain Heather, Alaska Heather, or Moss Heather, was known as Cassiope stelleriana until recently, and closely resembles the cassiopes. Alaska Mountain Heather differs in having alternate rather than opposite leaves, leaves spreading away from stem rather than appressed, and single upright rather than clustered and nodding flowers. It grows in alpine meadows and bogs from Mt. Rainier, Washington, to Alaska, and is not likely to be found below 5000 feet.

Kalmia microphylla, Alpine Laurel, Western Swamp Laurel, is an evergreen species into which a species, occidentalis, and several varieties were merged into one. It was also known as the species, polifolia, in the past. Its common name, laurel, is something of a misnomer in that the true laurel is of another family, Lauraceae.
        Alpine Laurel is an erect, branched plant that can become matted and spread by rooting of its layered branches. It can grow to nearly 2 feet, but is often little more than half that. The alternate, opposite, or whorled leaves are to 1 inches long and a fourth or less as wide, revolute or flat, dark green, glabrous on upper side, and pointed. Underneath the leaves are grayish and very finely glandular-hairy.
        Flowers are a colorful deep pinkish-rose in clusters at top of leafy stem. The petals are united from their base for about three-fourths their length, forming a slightly cup-shaped flower to inch wide. A fascinating feature of kalmias is the anthers which, when flowers are in bud, are recessed in pronounced sacs in the corolla wall, from which the anthers spring as the flower opens or is visited by pollinators.
        Alpine Laurel grows in sphagnum bogs near sea level and in subalpine and alpine mountain meadows and bogs, from Alaska south to northern California, east to Colorado and eastern Canada.

Kalmia microphylla
Kalmia microphylla in Cascade Mountains.
Photo by Wilbur L. Bluhm

Kalmiopsis leacheana, Kalmiopsis, is found only in southwest Oregon, in Siskiyou Mountains. For Lilla Leach of Portland, Oregon, who discovered the plant in 1930, K. leacheana was named. For Kalmiopsis leacheana the Kalmiopsis Wilderness in Curry and Josephine Counties was named. Here it grows at elevations from 500 to 6000 feet.
        A second form, K. "fragrans", Fragrant Kalmiopsis, grows to the northeast of the Kalmiopsis Wilderness in Douglas County, Oregon. It is the disjunct form of Kalmiopsis found in the Cascades Range, as opposed to the K. leacheana populations found in the Siskiyous. In the Cascade Mountains Fragrant Kalmiopsis has been reported at elevations from 2200 to 3500 feet.
        Summers in the Siskiyous are very dry and warm to hot, 90s to 100sF, with low relative humidity. Winters are relatively wet with rain and snow. In Cascades summer temperatures are not quite as high, but winters are similar.
        Both Kalmiopsis are attractive flowering, low growing, freely branched, evergreen shrublets to about a foot high. Leaves are numerous, thick, dark glossy green, oval, ⅓ to inch long, a third or half as wide as long. On underside the leaves are densely glandular-dotted.
        Flowers are deep rose, paler toward base. The wide open, campanulate flowers are to inch or more wide, and in terminal erect clusters of five to ten flowers. Kalmiopsis are the only heterostylic plants in the family Ericaceae, that is, having flowers with different length styles within the same species.
        Fragrant Kalmiopsis differs from Kalmiopsis in having larger corollas, longer anthers, much more pubescence on filament bases, and in producing copious nectar, for which K. leacheana is not noted.
        Flowers and foliage endear the plants to gardening enthusiasts. A well drained, relatively dry, peaty soil offers possibility for garden success, in sun or partial shade.

Kalmiopsis fragrans, in 
flower
Kalmiopsis "fragrans", in flower, Douglas County, OR.
Photo by Wilbur L. Bluhm

Both Ledum species are evergreen, leathery leaved plants sometimes found in wet areas. Leaves are often revolute-margined, usually conspicuously glandular, at least in the inflorescence. Their numerous white flowers are in tight clusters at end of twigs, each flower petal distinct to the base.
        The two species, L. glandulosum and L. groenlandicum, are easily distinguished by under leaf surfaces, greenish or white on the former and rusty-woolly on the latter.
        Ledums can be nice garden shrubs, even though they tend to be bog plants. A bog or very wet soil is unnecessary. They seem to thrive in a moist soil, and have thrived in seasonally rather dry soils.
        The common name, Labrador Tea, comes naturally. A tea can be brewed from the leaves, of L. groenlandicum, but apparently not from L. glandulosum and its varieties, which have the reputation of being poisonous.
        This genus is a prime candidate to become species of Rhododendron. Although not all yet agree, some botanists have made the change.

L. glandulosum var. columbianum, Coastal Labrador Tea, is found along the coast from Vancouver Island, British Columbia south to near San Francisco, California, in wet areas, often with standing or moving water. It is from a foot to rarely 6 feet tall with 1 to 2 inch long and nearly inch wide leaves that have strongly inrolled margins. Leaves are dark green on upper surface. Lower surface is lighter green or grayish, densely glandular, and sometimes hairy. Seed capsules are oval in shape. If this variety is to be reclassified to a Rhododendron it apparently would become Rhododendron columbianum.

L. glandulosum var. glandulosum, Western Labrador, or Trapper's, Tea, is more of a mountain plant on east side of Cascades in southern British Columbia and Washington, in northeast Oregon, Idaho, and to Rocky Mountains. It grows in moist seeps and swales under conifers. Its 1 to 2 inch long leaves are half as wide as long, either flat or slightly in-rolled. Seed capsules are nearly globular. It has a more compact growth habit than other Labrador Teas, increasing its garden desirability.
        If reclassified as a Rhododendron, it becomes Rhododendron neoglandulosum.

L. glandulosum ssp. olivaceum, Bog Labrador Tea, grows in southwestern Oregon and likely into northern California in or near wet places. It is very similar to Coastal Labrador Tea (above), a principal technical difference being that Bog Labrador Tea has an ovoid seed capsule and Coastal Labrador Tea an elongated one.
        If this subspecies is reclassified as a Rhododendron it is unknown what its botanical name may become, possibly due to relative recent verification of this subspecies.

L. groenlandicum, Bog Labrador Tea, is an erect shrub to 3 feet tall from Alaska south to Washington and east to Labrador and New England, commonly in muskeg, swamps, bogs, and moist coniferous woods. In the past it was reported in Oregon, but this may have been in error. Its dark green leaves, reddish brown woolly on under surface, are distinctive.
        This plant gives the common name, Labrador Tea, to all in the genus. Tea from its dried leaves was well known during Revolutionary War, and is apparently still widely used by Eskimos and other Arctic inhabitants. The tea tastes very much like green tea and it's been suggested it be taken in small quantities. Kruckeberg says, "Lest you plan a Labrador Tea orgy, the precaution of one or two changes of boiling water should be noted," it potentially having narcotic properties.
        With the strongly aromatic fragrance of its leaves came many uses of Labrador Tea over the centuries. It was laid among corn in barns to drive mice away, kept in bedrooms to disperse fleas, and in closets to repel moths, and possibly other uses. If ledums become rhododendrons this species would be named Rhododendron groenlandicum.

Ledum groenlandicum
Ledum groenlandicum, notice leaf underside.
Photo by Wilbur L. Bluhm

Leucothoe davisiae, Western Leucothoe, or Sierra Laurel, has a limited range in southwest Oregon and Northern California. Foliage and flowers remind one of the "doghobbles" of eastern United States. Its stems may be to nearly 5 feet long or tall, but usually much less. The evergreen, alternate, leathery, and glabrous leaves are oblong to elliptic, no more than 2 inches long.
        The many white, to ⅓ inch, urn-shaped flowers are borne on upright stalks in axils of upper leaves.
        Although Western Leucothoe grows in bogs or wet areas, it readily adapts to moist places in the garden. It can be a useful and attractive groundcover.

Loiseleuria procumbens, Alpine Azalea, or Trailing Azalea, range has been greatly extended as a choice prostrate small shrub for rock gardens, to 8 inches high. In the Pacific Northwest it is found in western British Columbia and northern Washington Cascades, in its greater range from Alaska to Greenland and northeast United States.
        Alpine Azalea grows in alpine and arctic tundra, gravelly slopes in higher mountains, sandy barrens, and peaty soils on the coast. The leathery, mostly opposite, evergreen leaves, less than a third inch long, have in-rolled margins. The light to deep pink flowers have fused petals for more than half their length, the 1/6 inch lobes flaring out to form a campanulate flower.

Menziesia ferruginea has no shortage of "common" names - Mock Azalea, Fool's Huckleberry, Rusty Menziesia, False Azalea, Rustyleaf...take your pick. It is an erect, somewhat straggly, shrub to 6 feet or more. Leaves are deciduous, thin, light green, sparingly hairy, glandular, finely toothed with hairy margins (ciliate), 1 to 2 inches long, more or less elliptic. The urn-shaped, to ⅓ inch flowers hang in clusters at end of shoots. They are yellowish tinged with red. The seed capsule is ovoid and about the size of the flowers.
        Mock Azalea grows in moist woods and on stream banks from Alaska to northern California and east to Rocky Mountain states, from near sea level to 4000 feet or so. It is a garden worthy plant. A blue leaf form is available.
        This is another candidate for reclassification to genus Rhododendron. It is not certain what botanical name might be assigned to Menziesia ferruginea.

Menziesia ferruginea
Menziesia ferruginea in Cascade mountain foothills.
Photo by Wilbur L. Bluhm

Moneses uniflora, Woodnymph, Single Delight, is, indeed, a delightful little evergreen plant, no more than 6 inches tall when in flower. The genus name, Moneses, comes from the Greek monos (single) and hesia (delight), alluding to the attractive solitary flower, a good fit for this rather delicate plant.
        The half dozen or so nearly round basal leaves, half to an inch long, with half to fully as long petioles, are no more than an inch or two above the soil surface. They are opposite and may be toothed.
        A waxy white to pinkish nodding flower is at top of a 1 to 6 inches tall stem. The 5 petals are ovate to nearly orbicular and spreading to form an open face flower. The 5 sepals, a fourth as long as the petals, are whitish with cilia on the margins. One must assume a very low position to look into the face of this little jewel.
        Its place is in damp woods and bogs, often on rotting wood, in shady coniferous forests, from sea level to well up in the mountains. Its range is from Alaska to California's Central Valley and Idaho, across the continent to Greenland and south to Pennsylvania. Woodnymph is on both sides of Cascades in Pacific Northwest.

Orthilia secunda, Sidebells Pyrola, One Sided Pyrola, One Sided Wintergreen, another plant with a multitude of common names, was formerly known as Pyrola secunda, quite recently given its own genus name. Its wide range throughout North and Central America and Eurasia may contribute to its plethora of common names. In the west it is found from Alaska and Yukon to California.
        Look for it in dry to moist woods, usually under conifers, in mid and subalpine elevations. It can flower into August in the higher elevations. The light greenish or white, flaring cup-shaped, flowers are many in a one-sided, 6 to 20 flowered, raceme up to 8 inches tall. The 5 broadly oval, almost inch petals are distinct, each with 2 small tubercles (small swelling or projection) at its base. The style is exserted beyond the petals.
        Usually a single stem supports both the flowers and the 5 to 12 evergreen leaves. Each ovate to elliptic leaf, to 2 inches long, is clear green and clustered near base and on the lower stem. Sidebells Pyrola is wide spreading by slender rhizomes (underground stems).

The genus Phyllodoce consists of 8 species in the northern hemisphere. Three are found in Pacific Northwest. They are low growing, 6 to 18 inches tall, evergreen, alpine heath-like shrubs with prostrate or ascending branches. They often form extensive mats.
        Leaves are dark green, very narrow (linear), needle-like, little more than a half inch long, revolute, alternate, and closely crowded. The campanulate (cup-shaped) to narrow urn-shaped flowers are in clusters at the stem tips. Each of the 5 fused petals is seen only as a lobe on outer rim of the flower. Growing at high elevations, they flower relatively late, from June or July through August.
        The Phyllodoces are attractive ornamental shrubs, but very difficult to grow and flower.

Phyllodoce breweri, Brewer's Mountain Heather, is found only in northern California on Magee Peak, northerly from Mt. Lassen, on moist rocky slopes and meadows. The near inch cup-shaped flowers are pink to rose purple. The 10 stamens are exserted beyond the flower.

P. empetriformis, Red Mountain Heather has a more extensive range, from Alaska to northern California, east to Idaho, Montana, and Wyoming in the high mountains. The colorful cup-shaped flowers are pink to rose, a good inch long. The 10 stamens are included within the flower.

Phyllodoce empetriformis
Phyllodoce empetriformis in high Cascades.
Photo by Wilbur L. Bluhm

P. glanduliflora, Yellow, or Cream, Mountain Heather, ranges from Alaska south to Oregon and Wyoming on mountain slopes, rocky ledges, and open places near and above timberline, in habitats similar to Red Mountain Heather. The inch urn-shaped flowers are yellowish to greenish white, less attractive than Red Mountain Heather, but interesting. In profile they are reminiscent of a "cute" little pig's head. The style and 10 stamens are included.

P. intermedia, Hybrid Mountain Heather, is a hybrid of Red and Yellow Mountain Heathers. It is found only where both parent species are present. The flowers tend to be light pink, between cup- and urn-shaped.

The genus Pyrola includes 15 perennial, rhizomatous, and glabrous species of North America and Eurasia. Six species are native to Pacific Northwest. Another possible species, P. grandiflora, occurs in Alaska and northern Canada, outside of our earlier defined area.
        The name Pyrola is from the Latin diminutive of Pyrus, the pear tree, alluding to the similarity of leaves of some species to the shape of the pear.
        Northwest native species are rather low, evergreen perennials with slender creeping rhizomes. Leaves are mostly basal and rather thick, variously shaped according to species. Flower stems are leafless but with 1 to a few bracts usually at base of flower pedicel.
        Flowers are in terminal several-flowered racemes, and mostly nodding. The 5 flower petals are separated to base, usually concave, white to greenish or purple. Each flower has 10 stamens bent inward, and a style that may be straight or conspicuously bent to one side, often projecting beyond the rest of the flower. Upper 2 petals generally form a hood over upturned stamens.
        Most of the species grow in cool coniferous forests, sometimes in wet habitats. Pyrolas are the true wintergreen, though oil of wintergreen is from Gaultheria procumbens, an Eastern America plant.
        Several known hybrids exist where species overlap in their range. Included are Pyrola asarifolia X P. minor, and P. chlorantha X P. minor.
        Four known Pyrola species have leafless forms - P. asarifolia, P. chlorantha, P. dentata, and P. picta.
        This genus is occasionally split off from Ericaceae into its own family, Pyrolaceae.

Pyrola asarifolia ssp. asarifolia, Alpine Pyrola, Common Pink Wintergreen, or Bog Wintergreen, has beautiful rose-colored flowers, in 5 to 25 flowered racemes, at top of 6 to 16 inch flowering stems. At base of each flower pedicel (stalk) is a green bract that is 1 times, or less, as long as the pedicel, a significant subspecies identification feature.
        Leaves are dark green and shiny above, usually somewhat purplish on underside. They are almost round, elliptic, or ovate (egg-shaped), or often heart-shaped. There are very few, if any, rounded teeth on leaf margin.
        Alpine Pyrola has a wide range, from Alaska to northern California, across Canada east to eastern North America and eastern Asia. It grows in moist forests, and may also be found in swamps, bogs, and on stream banks. Elevation range is from about 500 to 10,000 feet, the highest in southern end of its range.

Pyrola asarifolia ssp. 
asarifolia
Pyrola asarifolia ssp. asarifolia.
Photo by Wilbur L. Bluhm

P. ssp. bracteata, Pink Wintergreen, or Long Bracted Wintergreen, differs slightly from Alpine Pyrola in its inflorescence and leaves. The green bracts at base of pedicels are often considerably greater than twice as long as the pedicels. The leaves are finely toothed, more so than Alpine Pyrola.
        Pink Wintergreen's range is less broad, from Alaska to northern California and east to Montana. It tends to grow in somewhat drier places, in moist to dry forests, at 300 to 6500 feet elevation range.

P. chlorantha, Green Flowered, or Greenish, Wintergreen, has white to cream to pale yellowish to pale green flowers. The racemes are mostly 2 to 10 flowered, at top of 2 to 10 inch high flower stems.
        Leaves are basal, to 1 inches long and to 1 inches wide, obovate to broadly elliptic, to almost round. The leaf petioles are usually longer than leaf blade. Leaves are pale green on upper surface, deeper green underneath.
        Green Flowered Wintergreen grows in moist conifer or mixed forests, from about 2000 to 10,000 feet. Its range extends from Alaska to northern Sierras in California, where it may no longer exist, east across Canada to Atlantic coast, and Eurasia.

P. dentata, Nootka Wintergreen, or Toothleaf Pyrola, range is much narrower, from southern British Columbia to Sierran California, east to Idaho, Montana, and Wyoming. It is found in dry coniferous forests, especially in Ponderosa Pine woods.
        The several leaves are basal, to 2 inches long, petioles as long as leaf blade, broadest above middle, pointed at base where they join the petioles, and leathery. They are glaucous and pale green or bluish green. The leaves are more or less toothed.
        The one to several flowering stems are 4 to 10 inches tall. At the top are 10 to 20, about inch wide, cream to greenish-white flowers. The style is strongly curved.
        Toothleaf Pyrola is sometimes considered a synonym of P. picta. The two species are very similar and often occur together. There are distinctive differences in the leaves and in minor features.

P. elliptica, White Wintergreen, or Shinleaf, is least common Pyrola in Pacific Northwest. It occurs in dry to moist woods in southern British Columbia and Idaho, east to Nova Scotia, south to New York, Illinois, and New Mexico.
        White Wintergreen's 2 to 20 flowered racemes are on stems up to 10 inches tall. It resembles P. asarifolia except in having white, cream, or greenish white flowers whereas P. asarifolia flowers are pinkish to rose-purple.
        Its leaves are similar to those of P. asarifolia. Both have rather large ovate to orbicular leaves, to 2 inches long and three-fourths as wide. White Wintergreen leaves have short, blunt teeth.

P. minor, Lesser, English, or Snowline Wintergreen; or Little Shinleaf, has a short, straight style that sets it apart from other pyrolas, which have elongated and curved styles. Also, Lesser Wintergreen flowers are much more globose, petals are smaller, and style is included within the flower, compared with the others. Seed set is far greater than for many ericaceous genera and other pyrolas.
        The 5 to 20 flowers in the crowded raceme are small, less than inch broad, on 4 to 8 inch flowering stems. The white to pearly, pale pinkish, or rose petals are little more than 0.1 inch long.
        Lesser Wintergreen leaves are broadly elliptic to rounded, from to 1 inches long, with petioles as long or longer than leaf blades. Small, blunt teeth are on leaf margins. The leaves are bright green and rather thin.
        Lesser Wintergreen grows in humusy coniferous forests, moist mossy woods, and damp mountain forests from an elevation of about 3000, or lower, to 11,000 feet. Its range is Alaska to southern California, in Rocky Mountains south to Colorado and Utah, east to Atlantic Coast and Greenland, and Eurasia.

P. picta, White Vein Pyrola, White Veined Wintergreen, Mottled Shinleaf, is perhaps the most distinctive and easily identified pyrola due to its whitish-lined leaf veins. The leaves are crowded at the base, to 2 inches long, ovate to elliptic-rounded, leathery, deep green with white veins, and usually somewhat purplish underneath. Occasionally the leaves may not have white veins, or some plants may be leafless.
        The reddish-brown flower stems are 4 to 10 inches tall, with a few to 25 flowers in a raceme at the top of flowering stalk. The nearly inch-wide flowers have to ⅓ inch long, oval-shaped petals, yellowish to greenish-white to purplish-colored, and backed by reddish sepals.
        White Vein Pyrola occurs in dry to moist humusy coniferous forests from 1200 to 9500 feet in its range. It occurs from southern British Columbia and southwest Alberta to southern California, from Montana and Wyoming to Colorado and northern New Mexico and Arizona.

Field identification of Rhododendron and related genera native to the Pacific Northwest Region of North America

I. Shrubs or small trees with leathery evergreen foliage.

1. Leaves quite large (8-20 cm. long); flowers pink (rarely white) in dense terminal clusters, each flower up to 4 cm. in length. Various habitats.   Rhododendron macrophyllum

2. Leaves much smaller, generally 2-6 cm. in length; flowers white, much smaller (rarely up to 1 cm. in length) occurring in dense terminal clusters.
A. Lower surface of leaves covered with rusty colored woolly hairs. Found in lowland Bogs.   Rhododendron (Ledum) groenlandicum

B. Lower surface of leaves smooth and white or greenish.
a. Leaves quite narrow (up to 1 cm. wide) with a strongly revolute leaf margin. Found in coastal bogs.   Rhododendron (Ledum) columbianum

b. Leaves much wider (twice as long as broad) with a flat to only slightly revolute margin. Found in montane habitats.   Rhododendron (Ledum) neoglandulosum

II. Shrubs or small trees with thin deciduous foliage.

1. Flowers white to pink and quite showy or at least prominent.
A. White flowers in clusters of 1-4 hanging from the axils of the leaves, bell-shaped with spreading petals. Leaves somewhat elliptic in shape, usually rather shiny on the upper surface. Found in montane forests.   Rhododendron albiflorum

B. White fragrant flowers often flushed pink and with orange or yellow markings, widely funnel-shaped and appearing in dense rounded clusters on the ends of the branches. Found in moist woods and clearings along the coast from S. Oregon to coastal and montane California.   Rhododendron occidentale
2. Flowers urn to bell-shaped or with small widely spreading petals, reddish-orange to yellow-brown or coppery in color, quite small and not really showy or prominent.
A. Flowers urn to bell-shaped in hanging clusters, reddish-orange to yellow-brown in color. Leaves generally quite hairy, usually rounded in shape with a toothed margin. Found in moist woods from the coast into the mountains.   Rhododendron (Menziesia) ferruginea

B. Flowers single on the ends of branches, flat in shape with 5 separate wide-spreading lobes, petals coppery in color. Foliage elliptic to oblanceolate in shape (more narrow than round), without teeth and quite smooth. Found in moist forests.   Cladothamnus pyroliflorus

This key does not include Ledum glandulosum ssp. olivaceum, due to recent verification.

Wilbur Bluhm is a member of the ARS Willamette Chapter and of the Willamette Valley Chapter, Native Plant Society of Oregon. He is retired from Oregon State University Extension Service where he was an Extension horticulturist, staff chairman of the office at Salem and now Professor Emeritas.


Volume 60, Number 4
Fall 2006

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