SECTION II
SPECIES INFORMATION

I. Allotropa virgata Torrey & Gray (Sugarstick)

Area of Application: Throughout the area covered by the Northwest Forest Plan.

A. Introduction

Allotropa virgata is a herbaceous, nongreen species in the Ericaceae plant family. Sugarstick and candystick are common names that are applied to this species.

Allotropa virgata is classified as a Survey and Manage Strategy 1 and 2 species under the FSEIS/ROD (1994). In Oregon, Washington, and California A. virgata has not been placed on any organizational or agency sensitive or special status plant species lists.

B. Unique Characteristics, Biology, and Ecology

Allotropa virgata is sometimes termed a "monotrope" referring to the species affiliation with the Monotropoideae, a subfamily of plants within the Ericaceae that lack chlorophyll.

The following technical description is from Lichthardt and Mancuso (1991):

Achlorophyllous, simple-stemmed herbs with single to numerous stems, originating from a diffuse, root system bearing branch roots and adventitious buds at intervals along its length; stems 1-4 dm (3.94-15.75 inches) tall, white and pink (red) striped, 5-10 mm (.19-.39 inches) thick, enlarged below-ground; leaves reduced, scale-like, pinkish to yellow-brown, linear lanceolate; inflorescence a terminal, elongate, spikelike raceme, 5-20 cm (1.97-7.87 inches) long; flowers axillary and exceeded by the subtending bract, often with 1-2 bracteoles below the calyx; sepals 5, distinct, white or pinkish to brownish, about 5 mm (.20 inches) long; corolla lacking; stamens 10, purplish, opening by basal (falsely terminal) pores, from about equal, to twice as long as, the sepals; pistol 5-capillary, styles very short, stigma shallowly 5-lobed; ovary superior, 5-celled, with axile placentation; fruit a capsule.

The following is a nontechnical description of Allotropa virgata: Fleshy, nongreen plants with single or more often clustered, unbranched stems bearing the flowers and small, pointed leaves. The thick, brownish-red stems stand up to 40 cm (15.75 inches) tall. Stems are striped vertically with red and white, this feature being most obvious toward the base of the stem (small stems may be solid red). Flowers are similar in color to the stem and round in outline. An important feature of the flowers is that they open outward, directly away from the stem, as opposed to turning down as in closely related species (see below). Standing dead stems from previous years are almost always present. Old stems are dark reddish-brown with no white, and hollow.

Allotropa virgata may be confused with other nongreen members of the Heath family, which often share the same habitat. Pterospora andromedea (pinedrops) has sticky, brown flowering stems that also dry and persist a long time after dying. Unlike Allotropa virgata, its flowers face downward, borne at the ends of delicate, reflexed pedicels. It is generally much taller than Allotropa virgata (3 dm [11.81 inches] to over 1 meter [39.37 inches]). Hypopitys monotropa (pinesap) is similar in height to Allotropa virgata, but is uniformly pinkish to straw-colored, drying to black. In flower, the main stem bends over (nods) distinctly, but straightens again as fruits develop.

Some nongreen orchids, especially Corallorhiza spp.(coralroot), are sometimes mistaken for Allotropa virgata. Coralroot has slender stems, rather variable in color from purplish to reddish-brown to albino. However, stems do not bear the small, pointed leaf blades always present on Allotropa virgata.

Allotropa virgata is a clonal species that spreads by rhizomes, bearing adventitious buds on an extensive root system. Each successive ramet apparently maintains ties to an established network of fully colonized mycorrhizal roots until such time that flowering can occur. Successive ramets may be as far as 1 m apart. In one case where there was a linear pattern of old stems, excavation revealed that the growth of the plant followed a buried log.

Because the species can spread vegetatively, there is some question as to how many genets actually occur in a population. This can lead to an overestimation on the number of distinct individuals actually occurring in a population (Dimling 1997a).

Allotropa virgata may not flower or emerge above ground every year, as documented for several close relatives. Although not known for Allotropa virgata, some individuals of achlorophyllous ericads may be dormant for as many as 13 years between flowering episodes. Dead stems, however, are thought to be visible for several years after flowering. Climatic conditions are also thought to play a role in the presence, absence, and abundance of stems visible in a given year with moisture being a possible limiting factor. Limited data on flowering frequency is available. It has been reported a perennial species. (USDA Forest Service and USDI Bureau of Land Management 1994b, Lichthardt 1995).

Although often referred to as a saprophyte, Allotropa virgata, like its nongreen relatives, is actually a mycotroph - a plant that obtains necessary nutrients and carbon compounds from a fungus associated with its roots. For Allotropa virgata, the mycorrhizal fungi are commonly associated with the roots of conifers such as Douglas-fir (Pseudotsuga menziesii) and lodgepole pine (Pinus contorta). In portions of the species' range some hardwood species may also serve as host trees (Lichthardt and Mancuso 1991). Rhizopogon vinicolor, Cenococcum geophilum and Tricholoma magnivelare (matsutake) have been observed to occupy the roots of Allotropa virgata (Castellano and Trappe 1985, Lichthardt 1995)

Because of its dependent nature, the habitat in which Allotropa virgata is found may primarily be a function of the requirements of the fungus, with important factors being those of the soil environment and the availability of host trees. Buried, rotten wood is one important aspect of Allotropa virgata habitat, probably because it retains moisture and provides mineral or organic substances essential to the associated fungus (Lichthardt and Mancuso 1991), especially during the dry season.

In Idaho, Lichthardt and Mancuso (1991) reported that the species could survive ground fires that do not affect overstory host trees. Such ground fires are generally cool burns in which the underground root system may not be adversely impacted (Dimling 1997a).

It is still not clear what the role of mammals is in the dispersal of Allotropa virgata. It has been suggested that both small mammals as well as ungulates such as deer, may be important in the dispersal of seed, but this would depend on seed being mature. Deer have been observed to routinely browse plants. It has also been suggested that browsing may impact the reproductive capacity of plants (Dimling 1997a). Deer tend not to compact or disturb the duff and soil layers associated with plants, which can occur with other grazing animals.

C. Specific Habitat Associations

Allotropa virgata occurs in closed canopy pole (Oregon coastal strand), mature, and old-growth seral stages in Pseudotsuga menziesii (Douglas-fir), Tsuga heterophylla (western hemlock), Abies grandis (grand fir), Abies amabilis (silver fir), Abies magnifica (red fir), Lithocarpus densiflorus (tan oak), and Pinus contorta (lodgepole pine) vegetation series, ranging from sea level along the Oregon coast to 3048.78 m (10,000 feet) at inland sites. It is not restricted to old-growth, but the largest populations occur there. It has been observed in 60-year old stands at inland sites with 4.33 cm (11 inch) diameter trees, but does not appear to tolerate competition in those conditions. U. S. Forest Service ecology program ecoplot data indicates that Allotropa virgata occurs in a wide range of plant associations and is often found in low densities within ecoplots. Most sites have less than ten stems; however, some populations have over 100 stems. Populations, although widespread, are often highly isolated. It often occupies dry, well-drained, acidic soils, with abundant coarse woody debris (especially decay classes 4 and 5). It appears substrate specific to decaying wood, with individuals at an Idaho site restricted to the buried margin of a partially decomposed log (USDA Forest Service and USDI Bureau of Land Management 1994b). Observations suggest that coarse woody debris is a critical habitat component for this species, providing moisture and nutrient reservoirs, especially during droughty summer months except within the Oregon coastal strand (Dimling 1997a).

The species occurs at elevations of 3.05-91.46 m (10-300 feet) within the Oregon coastal strand (defined as a 3-mile strip of land immediately adjacent to the Pacific Ocean) and is found strongly associated with 35-85 year old Pinus contorta forests in stabilized coastal dunes. Abundant summer fog in this area seems to alleviate the need for coarse woody debris, which is thought important as a moisture reserve in dryer conditions for the species' mycorrhizal host. Within the Oregon coastal strand, habitats that support and maintain populations of Allotropa virgata lack late-successional and old-growth characteristics, and Pinus contorta (lodgepole pine) is considered an early to mid-seral species in coastal forest development (Dimling 1997b).

In the California coast range and Klamath Mountains, Allotropa is closely associated with the tanoak series. Populations are found in early to mid-mature forests. Stands in the Coast Range exhibit evidence of fire history; most have remnant wolf trees.

Allotropa in the California Cascades is most abundant on the east side of the mountains. It is associated with Abies magnifica/Pinus contorta (red fir/lodgepole pine) associations at elevations above 5000 feet. In this part of the range, Allotropa is not associated with a deep duff layer.

Allotropa virgata is a achlorophytic (nongreen) species, requiring an association with a mycorrhizal associate (fungus) that in turn is dependent on a green vascular host. Within the range of the northern spotted owl, the primary photosynthetic hosts appear to be conifers, primarily Pseudotsuga menziesii (Douglas-fir) and Pinus contorta (lodgepole pine), but other conifers are probable. Competition between mycorrhizal mycelium from other vascular plant species may be a limiting factor in some Allotropa virgata habitat conditions. Some evidence suggests that it is necessary to maintain approximately 70 percent canopy closure to maintain mycorrhizal hosts and reduce increases in underground competition from other mycorrhizal species. Shifts in underground mycorrhizal species often leads to changes in the above ground plant communities (Dimling 1977b).

D. Known Range

Allotropa virgata occurs in deep humus of coniferous forests, from the east slope of the Cascades to near the coast, from British Columbia to California. The species is widespread, but rare throughout the range. Noteworthy disjunctions occur in Idaho and Montana. This species was thought to be rarely observed in California within the range of the northern spotted owl (USDA Forest Service and USDI Bureau of Land Management 1994b). Dimling (1997b) reported that out of 716 occurrences of Allotropa virgata, 30 were located in California, 74 were located in Washington, and 612 occurred in Oregon. The majority of sites from Oregon were found in the Cascades. Within the range of the northern spotted owl, the species occurs on several National Forests and BLM Districts in California, Washington, and Oregon.

E. Timing of Surveys

Surveys should be conducted during the flowering or fruiting period (May-September) when plants are easily seen and identifiable.

F. Threats

• Fragmentation of suitable habitat and loss of important genes
• Forest management activities such as thinnings, shorter rotations, regeneration harvest, road building, and mechanical disturbance to duff and soil layers
• Reductions in coarse woody debris inputs into Allotropa virgata habitat, below Northwest Forest Plan levels.
• Disturbance of duff or soil layers from activities such as unauthorized raking and digging activities associated with commercial and recreational matsutake mushroom and other activities that cause soil compaction.
• Trampling and plant collection from recreational activities, such as hiking and horseback riding along trails where Allotropa virgata occurs.
• Livestock grazing is occurring within Allotropa virgata populations and has been observed to cause the removal of reproductive stems from plants (Wogen and Lippert 1998).
• Browsing by deer and other mammals has been reported, which may reduce reproductive potential (Dimling 1997a).
• Noxious and exotic weeds in and around Allotropa virgata habitat.

REFERENCES

Castellano, M. A. and J. M. Trappe. 1985. Mycorrhizal associations of five species of Monotropoideae in Oregon. Mycologia 77: 499-502.

Dimling, J. 1997a. Allotropa virgata Meeting Notes, Umpqua National Forest. Unpublished Meeting Notes.

Dimling, J. 1997b. Allotropa virgata Habitat and Viability Analysis. Unpublished Meeting Notes.

Lichthardt, J. 1995. Draft Conservation Strategy For Allotropa virgata (Candystick). U.S. Forest Service Northern Region. Idaho Department of Fish and Game.

Lichthardt, J. and M. Mancuso. 1991. Report on the Conservation Status of Allotropa virgata (Candystick) on the Nez Perce National Forest I. Field Survey and First and Second-Year Monitoring Results. Idaho Department of Fish and Game. 16 pp.

USDA Forest Service and USDI Bureau of Land Management. 1994a. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Portland, Oregon.

USDA Forest Service and USDI Bureau of Land Management. 1994b. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Appendix J2, Results of Additional Species Analysis. Portland, Oregon.

Wogen, N. S. and J. D. Lippert. 1998. Management Recommendations for Candystick or Sugarstick (Allotropa virgata Torrey & Gray).