''Oxalis oregana'', known as redwood sorrel or Oregon oxalis, is a species of the wood sorrel family,

Oxalidaceae The Oxalidaceae, or wood sorrel family, are a small family of five genera of herbaceous plants, shrubs and small trees, with the great majority of the 570 species in the genus ''Oxalis'' (wood sorrels). Members of this family typically have divid ...

, in the genus ''

Oxalis ''Oxalis'' ( (British English) or (American English)) is a large genus of flowering plants in the wood-sorrel family, Oxalidaceae, comprising over 550 species. The genus occurs throughout most of the world, except for the polar areas; species ...

'' native to moist

Douglas-fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...

and

coast redwood ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995: 606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coast ...

forests of western North America from southwestern

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Washington Washington most commonly refers to: * George Washington (1732–1799), the first president of the United States * Washington (state), a state in the Pacific Northwest of the United States * Washington, D.C., the capital of the United States ** A ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, and northern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. The species is now recognized as distinct from '' Oxalis smalliana'', with which it was previously conflated.

Description

''Oxalis oregana'' is a short,

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

with erect flowering stems 5–15 cm tall. The three

leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

lets are heart-shaped, 1–4.5 cm long with purplish undersides, on 5–20 cm stalks. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is 2.4–4 cm in diameter, white to pink with five petals and

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s. The hairy five-chambered

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

capsules are egg-shaped, 7–9 mm long; seeds are almond-shaped. It spreads by a scaly rhizome varying the size of patches. They can be seen throughout moist forest under-canopies. The species ranges from southern Humboldt County, California to southwestern British Columbia. Unlike its close relative ''Oxalis smalliana'', ''O. oregana'' consistently has white flowers and shows typical single sequence haplotypes in genetic analyses. In areas where both species overlap, ''O. oregana'' reaches peak flowering approximately one month later than ''O. smalliana''.

Rapid light response

''Oxalis oregana'' photosynthesizes at relatively low levels of ambient sunlight (1/200th of full sunlight). When direct sunlight strikes the leaves, they fold downwards; when shade returns, the leaves reopen. Taking only a few minutes, this movement is observable to the eye.

Taxonomy

''Oxalis oregana'' has historically been confused with ''Oxalis smalliana'', which was first proposed as a separate species by R. Knuth over a century ago. Genetic studies published in 2022 confirmed that they are indeed separate species, with ''O. oregana'' and ''O. smalliana'' showing divergence at both nuclear and chloroplast loci. The two species overlap in range in the Klamath Range of northwestern California and southwestern Oregon.

Leaves as food

The leaves of ''Oxalis oregana'' are eaten by the Cowlitz,

Quileute The Quileute () are a Native American people in western Washington state in the United States, with 808 enrolled citizens in 2018. They are a federally recognized tribe: the ''Quileute Tribe of the Quileute Reservation''. The Quileute people ...

and

Quinault Quinault may refer to: * Quinault people, an Indigenous people of the Pacific Northwest Coast **Quinault Indian Nation, a federally recognized tribe ** Quinault language, their language People * Quinault family of actors, including: * Jean-Bapt ...

peoples. Like

spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to Central Asia, Central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common vegetable consumed eit ...

, they contain mildly toxic

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula , also written as or or . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name i ...

, which is named after the genus. They are safe to eat in small amounts for those with no oxalate-related conditions.

References

External links