The Ericaceae of the Pacific Northwest, Part V
Wilbur L. Bluhm
Part I of the series, which began in the spring 2006 issue of the Journal, led with a general discussion of the family Ericaceae , and overview of the Northwest Ericaceae and description of two NW ericaceous species. Part II contined with plant descriptions of NW species in the genus Arctostaphylos . Part III covered genera Cassiope through Pyrola . Part IV covered genera Rhododendron and Vaccinium . In this issue, Part V deals with the Monotropoideae .
These are the nonphotosynthetic Ericaceae , among the most interesting and spectacular in the family. All are colorful; some are brilliant. The stalks and scale-like leaves have no chlorophyll.
Without photosynthetic ability, these plants are dependent upon other plants, known as autotrophs, for their growth and sustenance. They achieve this with "nutrients" coming via a pathway, through fungi, from roots of autotrophs to roots of the monotropes. The fungi, known as mycorrhizae or mycorrhizal fungi, also gain from this mutually beneficial system. With at least some of the monotropes, their roots are entirely sheathed by their associated mycorrhizal fungi, so there is not contact between roots and soil.
Many different genera and species of fungi are mycorrhizal. Some are the common mushrooms that grow around us. Specificity of mycorrhizal fungi for monotropes is remarkably high and has been determined for many ericaceous species.
Dr. Daniel Luoma, Forest Sciences Laboratory, Oregon State University says, "Generally, a given plant will have only one fungus (species) on its root system. I do have a root system of Pterospora in my lab that has one root tip of a second fungus, the rest are covered with Rhizopogon salebrosus . There is some regional variation, but the fungi associated with a particular monotrope species are closely related. Not too surprisingly, the most widespread monotrope, Monotropa hypopitys , has the most diverse set of symbiotic associates."
Mycorrhizae associated with monotropes have been called the "monotropoid mycorrhizae," distinguishing them from various other mycorrhizae. Within them, research indicates that plant lineages are specifically dependent on different lineages of fungi in the monotrope mycorrhizal symbiosis. For example, a different species of the fungus Rhizopogon is associated with each, different, lineage of Pterospora andromedea , Pinedrops.
Also, it's been shown that stimulation by a Rhizopogon fungus may be necessary for germination of Pinedrops seeds, which may also be necessary for other monotropes. Rhizopogon fungi are said to be exclusively associated with conifers of Pinaceae family, especially with genera Pinus and Pseudotsuga , and possibly Abies , and that each Rhizopogon species may be associated with a single conifer genus or species.
Dr. Luoma adds, "Which autotrophic plants are suppling the carbon is governed by the host specificity of the fungi. In Oregon, most of the fungi involved form ectomycorrhizae with members of the Pinaceae , especially Pinus and Pseudotsuga . However, it has been found that Tricholoma magnivelare , host to Allotropa virgata , can simultaneously form mycorrhizae with Pinus , Pseudotsuga , Arbutus , and Lithocarpus . It is possible that Arctostaphylos could also be involved since it has the right type of mycorrhizae (ecto). A vast majority of herbs and most shrubs have arbuscular (or some other incompatable) mycorrhizae, so can not be involved." (See Table 1.)
|Table 1. Pacific Northwest Monotropoideae and symbiotic associates based on knowledge as of 2005, by Daniel L. Luoma.|
|Monotrope||Fungal hosts||Autotrophic carbon source|
|Allotropa virgata||Tricholoma magnivelare (American matsutake)||Usually Pinaceae , Arbutus and also Lithocarpus|
|Hemitomes congestum||Hydnellum peckii and H. spp. (mushrooms)||Pinaceae|
|Monotropa hypopitys||Tricholoma spp. - T . equestre most commonly in NA (mushrooms)||Usually Pinaceae , Quercus and Salix also (in Eurasia)|
|Monotropa uniflora||Russula spp. and Lactarius theiogalus , R. brevipies commonly in NA (mushrooms)||Pinaceae and Fagaceae|
|Pityopus californicus||Tricholoma myomyces (and other T . spp.)||Pinaceae|
|Pleuricospora fimbriolata||Gautieria monticola (truffle)||Pinaceae , esp. Pseudotsuga|
|Pterospora andromedea||Rhizopogon salebrosus and R. arctostaphyli (truffles)||Mostly Pinus but also Pseudotsuga|
|Sarcodes sanguinea||Rhizopogon ellenae and R. atroviolaceus (truffles)||Pinus and Abies|
By virtue of this mycorrhizal relationship the monotropes are parasitic plants, more specifically non-photosynthetic mycorrhizal epiparasites. Before this was known they were thought to be saprophytes, deriving nutrients from decaying plant matter in the soil; or symbiotic saprophytes, having a mutual association with saprophytic fungi; or root parasites of autotrophs, deriving nutrients directly from roots of photosynthetic plants.
Monotropes are all deciduous, dying after flowering and fruiting, though some may persist for awhile. Only the annual inflorescence, the flowering and fruiting stalk with its leaves, appears above ground. It arises and grows upright from adventitious buds on the perennial succulent roots, which are also brittle. The stalk is fleshy with some genera. With the more slender-stemmed genera, flowers typically occupy the upper one-third to one-half of the stalk. Leaves on the stalk are scale-like, bearing the color of the plant as a whole.
The inflorescences of the following species are racemes, with lowest flower the first to open, flower-opening then progressing upward to the top of the stalk. The exceptions are mentioned with the species. In some of the genera a bract attached at base of flower stem (pedicel) covers the developing flower until it opens.
Flowers are variable among the genera. Fruits are capsules, usually with many small seeds in each chamber. Capsules are sometimes fleshy and resemble a berry.
It's been suggested that pigments and tannin in monotropes probably make the plants unpalatable to animals, although there is an occasional appearance of minimal grazing.
, Sugar Stick, Candystick
is striped white and pink, red, maroon, or purplish black somewhat like a barber's pole, but with longitudinal stripes. The 10 stamens and large disk-like stigma face outward past the 5 distinct petals. They are same color as the colored stripes, which altogether makes for a striking plant.
Sugar Stick grows from about 6 to 16 inches, occasionally taller, with a stalk to almost ⅓ inch thick, singly or in clusters. It inhabits humus in oak, coniferous, and mixed forests from near sea level to nearly 10,000 feet, from east slope of Cascade Mountains west to coast, southern British Columbia to northern California.
, Sugar Stick.
Red pistil and stamens.
Photo by Wilbur L. Bluhm
, Gnome Plant
is a waxy, whitish to cream to fleshy-pink colored, low-growing plant, 1 to 7 or 8 inches tall, singly or with numerous plants in a cluster.
Flowers are congested in the inflorescence. The 4 petals are united for half their length to form a tubular flower. Sepals and petals are same color as stalk and leaves. The prominent stigma is bright yellow, courted by 8 yellow stamens next to it. The fleshy stalk may be an inch, more or less wide, widest near the top below the flowers. Flowers may be in a flat-topped cyme, a raceme, or solitary.
Gnome Plant grows in deep humus under trees in coniferous or mixed forests. It ranges from southern British Columbia, Washington's Olympic Peninsula, south to Monterey County California, from the Cascade and Siskiyou Mountains to the coast, at elevations near sea level up to 5200 or more feet in Oregon and 8800 feet in California.
, Gnome Plant.
Photo by Wilbur L. Bluhm
has straw-colored, yellowish, or pinkish stalks, leaves and flowers, which dry to black after flowering. It may grow from 2 to nearly 20 inches tall on a stalk more slender than that of Gnome Plant, singly or in few-plant clusters. The 4 (3-5) flower petals, though distinct to base, form an enclosed tube. Whereas most monotropes flower during spring, Pinesap appears on drying forest floors during summer. Fruits are fleshy capsules resembling a berry.
Pinesap grows in rich humus in mixed and coniferous forests at elevations from near sea level to almost 9000 feet. In the Northwest it ranges from Alaska southward to northern California and east to Idaho. Its broader range extends to eastern U.S. and adjacent Canada to Atlantic Ocean, Mexico, and Eurasia.
Pinesap was formerly named Hypopitys monotropa .
Photo by Wilbur L. Bluhm
, Indian Pipe
is waxy-white with a single nodding flower at top of stalk, becoming erect in fruit (capsule). It ages to black. Indian Pipe may grow from 2 to 10 or more inches tall, singly, or, more commonly, in many-stalked clusters. The 5 (4-6) flower petals, though distinct, form a more or less enclosed tube, somewhat flared at top, narrower in middle, and wider at base. Tilting the flower up reveals a large yellow disk-like stigma surrounded closely by 10 yellow stamens. Fruits are subglobose, fleshy capsules.
Indian Pipe grows in dry, generally deep shaded, coniferous and mixed woods, from near sea level to 6000 feet or more in mountains. In the Northwest it is found from Alaska and British Columbia, Washington, Oregon, to northern California and Idaho. Its greater range extends east to Atlantic Coast, Central and South America, and Asia. It is one of more common monotropes in the Northwest.
, Indian Pipe. Cluster in Cascade Mountains.
Photo by Wilbur L. Bluhm
plants have white to yellow to pinkish stalks, leaves, and flowers, which dry to black. Plants appear singly, from 2 to 10 inches tall, with fleshy stalks that are widest just below the single or raceme of flowers. The 4 (5) distinct petals form a cylindric tubular corolla, enclosing a prominent yellow stigma and 8 stamens.
So seldom seen for so long, considered very rare, Pinefoot has not appeared much more in recent years, even under the scrutinous eyes of plant seekers, and remains uncommon to rare throughout its range. It occurs west of Cascade summit in Oregon to the coast, from Linn County, Oregon south into Siskiyou Mountains and to Bay Area of California. It grows in deep humus of coniferous and mixed forests, at elevations from near sea level to about 5500 feet.
, Pinefoot. Emerging through moss on forest floor.
Photo by Wilbur L. Bluhm
, Fringed Pinesap
is a whitish to yellow-brown plant, growing singly, 1 to 5, occasionally 7, inches tall, with fleshy stalks. The 4 (5-6) distinct petals and sepals form a tubular flower, flaring out at top, narrower in middle, and wider at base. The style, stigma, and stamens tend to be hidden within the tube. Fruits are fleshy capsules.
Fringed Pinesap is a resident of deep forests, coniferous and mixed, barely emerging from the duff. It grows in Olympic Mountains of Washington, southward on west side of Cascade Mountains to the coast, and south to Sierra Nevada Mountains of central California. Fringed Pinesap grows from just above sea level to about 9000 feet in southern end of the plant's range.
, Fringed Pinesap.
Photo by Wilbur L. Bluhm
has attractive cream to pink, reddish, or purplish colored stalks, leaves, sepals, and sterile bracts, one at base of each flower pedicel. All are glandular-hairy and very sticky. The stalks gradually decrease in thickness from base to top of the inflorescence.
The numerous urn-shaped corollas, cream to yellowish or white, or occasionally pinkish, lighter colored than the stalks and sepals, hang like little bells from a pole. The first flowers do not open until about four weeks after the plant emerges through the duff.
Pinedrops is 1 foot to 3 feet tall, singly or several in clusters from a single root mass. They are the tallest of the Northwest monotropes. Though associated with other conifers they seem especially prevalent with Pinus ponderosa , the yellow pine. After seed dispersal the plants are very persistent, often standing as dried sentinels for a year or two in the forests they inhabit.
Pinedrops grows in deep humus in coniferous or mixed forests from about 50 to 12,000 feet. They are found in southern half of British Columbia, southward through Washington and Oregon, on both sides of Cascade Mountains, but uncommon along coast and west of the bases of Cascade and Siskiyou Mountains, to southern California, and Idaho. The range extends east across Canada and U.S. to the Atlantic, into Rocky Mountains and south to Mexico.
West of Cascade summit.
Photo by Wilbur L. Bluhm
In past years the name Pyrola aphylla was applied to the now known four leafless Pyrola species - P. asarifolia , P. chlorantha , P. dentata , and P. picta , all previously discussed. The leafless forms are typical of the species, but without green leaves. They may be "normal" plants growing on stored nutrient reserves in lieu of having leaves, or they may have a mycorrhizal relationship.
, Snow Plant
has very showy, brilliant red stalks, scale-like leaves, flowers, and flower bracts. It is 3 to 12 inches tall, fleshy, single or in clusters of 15 or more plants. Plants are persistent after seed dispersal, "in the dull and drab tones of fall" (Wiley).
The 5 petals are fused most of their length to form an urn-shaped corolla. The 5 distinct sepals are about three fourths as long as the corolla. The many to inch flowers on each stalk point more or less outward to show the yellowish or reddish head-like stigma and the 10 dark-colored anthers.
Snow Plant grows in coniferous and mixed forests in middle to high mountain elevations, from about 2200 to above 10,000 feet. Its northern most range is the Cascade and Siskiyou Mountains of southern and southwest Oregon, then into northern California, south to the San Jacinto and Santa Rosa Mountains of southern California.
The curious name, Snow Plant, alludes to the plants emergence through or just after the receding snow line in early spring, though plants continue to be seen long after snow disappears.
, Snow Plant.
Cook and Green Pass, Siskiyou Mountains.
Photo by Wilbur L. Bluhm
Field Key to the Monotropoideae of the Pacific Northwest
. Daniel L. Luoma, 2000
1a. Plants low to the ground at maturity, old stalks not persistent, fruit a berry, seeds attached to inward projections from the berry wall, style and ovary merge smoothly.
2a. Petals united, hairy on inner surfaces, flowers in a dense head, usually just emerging from duff, pink when young, fading to straw-colored. . . . . . . . . . . . . Hemitomes congestum
2b. Petals free, flowers in a more elongated raceme, cream to straw-colored, elevated somewhat more above the duff.
3a. Petals densely hairy within, anther round. . . . . . . . . . . . . . . . Pityopus californicus
3b. Petals not hairy, margin fimbriate, anthers elongate. . . . . . . . Pleuricospora fimbriolata
1b. Plants not low to the ground at maturity, old stalks often present, fruit a capsule, seed attached to a central column, style not evenly continuous with ovary.
4a. Plants bright red or red and white striped when fresh.
5a. Plants bright red, fading to brownish red, capsule hard and shining, seeds round, about 1 mm in dia., not known north of Douglas County, Oregon. . . . . . . . . Sarcodes sangunea
5b. Plants red and white striped, pale when emerging and staining green at times, drying to black, flowers open and shallow with stamens exerted. . . . . . . . . . . . . Allotropa virgata
4b. Plants pinkish, to dull orange, to straw colored or brick red-brown.
6a. Petals free, flower stalks emerge bent over.
7a. Flower stalks with only one flower, white. . . . . . . . . . . . . . . . . . . . . . . . . . Monotropa uniflora
7b. Many flowers on a stalk, pink (rarely red) to orange to straw colored . . . . . Monotropa hypopitys
6b. Petals united, stalk emerging erect, usually orange-brown to brick red-brown but may be yellow, tall (may reach 1meter). . . . . . . . . . . . . . . . . Pterospora andromedea
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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.