Wood-sorrel

Oxalis oregana

Range

Washington, Oregon and northern California, rare in alluvial forests of western Vancouver Island and Queen Charlotte Islands (4).

Climate, Elevation

Temperate climates at low to medium elevations (4).

Local occurrence (where, how common)

In deep shade of mature alluvial forests.

Habitat preference

Productive forest sites with high precipitation and fertile soil (2, 4).

Plant strategy type/successional stage

Requiring moist conditions, it forms understory groundcover in late successional conifer forests (1).

Associated species

Sitka spruce (Picea sitchensis), Douglas-fir (Pseudotsuga menziesii), sword fern (Polystichum munitum), western trillium (Trillium ovatum), salal (Gaultheria shallon), and deer fern (Blechnum spicant). In northern California, coastal redwood (Sequoia sempervirens) associated overstory conifer species (1).

May be collected as

Divisions in mid September (5).

Collection restrictions or guidelines

Remove all but one or two leaves from plant division. Each division must contain a root or rhizome mass. (5).

Seed germination

Seeds require no seed pretreatment. Other members of the Oxalis genus are weedy pests in greenhouse environments (6). Seeds planted in cold frame in late winter to early spring. Transplant seedlings into individual pots when large enough to handle and plant in late spring or early summer (3).

Seed life

Short shelf-life, best if sown as soon as ripe (3).

Propagation recommendations

In restoration practices, propagation of divisions from vicinity of site is recommended. Seeding is also an option, but no success rates were found.

Soil or medium requirements

In field, moist humus. In nursery environment, standard potting mix of peat moss, fir bark, perlite, and sand (5).

Installation form

Transplanting divisions is cheap and survival averages 90% (5).

Care requirements after installed

Water transplanted divisions in well. No additional watering requirements specified (5).

Normal rate of growth or spread; lifespan

Can be an aggressive groundcover in appropriate growth conditions (3).

Sources

1. Fire Effects Information System, USDA FS. www.feis.org

2. Gifford Pinchot National Forest, USDA FS. www.fs.fed.us/gpnf/forest-research/ei/special/species/herbs/oxor.html

3. Plants for a Future, University of Leeds. “Oxalis oregana” http://www.scs.leeds.ac.uk/cgi-bin/pfaf/arr_html?Oxalis+oregana&CAN=LATIND

4. Pojar, J. and A. MacKinnon. Plants of the Pacific Northwest Coast-Washington, Oregon, British Columbia and Alaska. B.C. Ministry of Forest and Lone Pine Publishing. 1994.

5. Young, Betty. Oxalis oregana protocol information. NPS, Golden Gate National Park. http://www.nativeplantnetwork.org/network/view.asp?protocol_id=655,656

6. Young, J. and Cheryl G. Young. Collecting, Processing, and Germinating Seeds of Wildland Plants. Timber Press, Portland, Or: 1986.