Courtesy of Texas A&M University Herbarium
Distribution map of O. montana in United States

Courtesy of The University of Tennessee Herbarium
Distribution of O. montana in Tennessee

Common woodsorrel is a dominant understory species in the northern hardwood forest, red or sugar maple, yellow birch, and American beech. It is also a dominant species in the transition plant associations between the boreal forest and the northern hardwoods. It is a minor component of the riparian communities in the northern hardwood forests. Frequent herbaceous codominants are false lily-of-the-valley, goldthread, starflower and woodferns. Associated understory species include lowbush blueberry, witherod, hobblebush and bunchberry (Pavek, 1992).

Common woodsorrel is a climax understory species. It is a tolerant species under mature fir canopy with low levels of light. Common woodsorrel is present in, although not characteristic of, early or mid- seral stages in New England’s northern hardwood or spruce-fir boreal forests. Disturbance occurs as severe winds, hurricanes, and fire (Pavek, 1992).

Common woodsorrel is found in soil with a pH which is strong to moderately acidic. A study conducted on O. montana in Finland (Viitaniemi Comprehensive School, 1998) found that the plant existed in soil with pH ranging from 4.3 in the less fertile areas up to a pH of 5.7 in the more lush areas. Saturated soils may be poor to moderately well drained. Soils are generally poorly developed and often consist only of an organic mat on top of bedrock. It is known as a soil stabilizer because it has extensive clonal growth and the ability to grow on steep ground, poor soil and in deep shade. It has been discovered from level to steep slopes. O. montana has been found to exist at 500 feet in Maine coastal forests to 5,000 feet in the Smoky Mountains of Tennessee and North Carolina (Pavek, 1992). O. montana is known to grow in full shade and direct sunlight but is more often found in a shadier environment.

The growing season throughout its range is from 110 to 140 days and is relatively cool with ample moisture in the soil. The average annual temperatures are less than 60 degrees Fahrenheit. Moss coverage can be low to high, and a high fern coverage will reduce O. montana populations (Pavek, 1992).

Common woodsorrel reproduces both sexually and asexually. Asexual flowers (cleistogamous) produce greater amounts of seed compared to sexual flowers. Total fruit set per plant is low because there is only one flower per stalk. Mature capsule dehisce seeds forcefully, flinging them outward from the plant (Pavek, 1992).

Life cycle and Population Dynamics

Reproduction usually involves episodes of seedling recruitment as a result of disturbance, such as fire and logging, followed by long periods of vegetative clonal growth. Common woodsorrel forms extensive colonies, however, its colonies rarely exceed several feet in diameter (Pavek, 1992).

Most plant growth will occur before the flowers are out. In a population, the flowering period will last approximately 30 days, with individual flowers open for about five days. Fruit maturation takes about 12 days and requires warm days prior to dehiscence. The seeds are shed from June to September throughout its range (Pavek, 1992).

How to encounter

The common woodsorrel, O. montana, grows abundantly in shaded woods as a forest understory.   It is most commonly found in spruce-fir boreal forests in shady patches. The asexual flowers can be encountered from June through September, whereas the sexual flowers are abundant from May to July. O. montana is very abundant in the Smokey Mountains along the Tennessee, North Carolina border in the lush growth forests. It is most likely to be encountered at the higher altitudes. O. montana does tend to form cohorts of a relatively good size so that you would not have to look hard for an individual species when searching.

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Fernald, M. L. 1950. Gray’s Manual of Botany. American Book Company. New York, NY.

Gleason, H. A., A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada 2^nd Edition. The New York Botanical Garden. Bronx, NY.

Pavek, D. S. Oxalis montana. 1992. The Fire Effects Information System [Data base]. Department of Agriculture, Forest Service, Intermountain Research Station, Intermountain Fire Sciences Laboratory.

Porter, C. L. 1967. Taxonomy of Flowering Plants. W. H. Freeman and Company. San Francisco, CA.

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University of Georgia Herbarium. University of Georgia. Copyright 1999.
Internet References