Crooked Run Valley
common yellow oxalis (Oxalis stricta)
yellow wood sorrel
common yellow oxalis
tall yellow wood sorrel
upright yellow wood-sorrel
Ceratoxalis coloradensis (Rydb.) Lunell
Ceratoxalis cymosa (Small) Lunell
Oxalis brittoniae Small
Oxalis bushii (Small) Small
Oxalis coloradensis Rydb.
Oxalis corniculata var. dillenii (Jacq.) Trel.
Oxalis cymosa Small
Oxalis dillenii Jacq.
Oxalis dillenii ssp. filipes (Small) Eiten
Oxalis dillenii var. radicans Shinners
Oxalis europaea Jord.
Oxalis europaea var. bushii (Small) Wieg.
Oxalis europaea var. rufa (Small) Young
Oxalis filipes Small
Oxalis florida Salisb.
Oxalis florida ssp. prostrata (Haw.) Lourteig
Oxalis florida var. filipes (Small) Ahles
Oxalis fontana Bunge
Oxalis fontana var. bushii (Small) Hara
Oxalis interior (Small) Fedde
Oxalis prostrata Haw.
Oxalis rufa Small
Oxalis rupestris Raf.
Oxalis stricta var. decumbens Bitter
Oxalis stricta var. piletocarpa Wieg.
Oxalis stricta var. rufa (Small) Farw.
Oxalis stricta var. villicaulis (Wieg.) Farw.
Xanthoxalis brittoniae (Small) Small
Xanthoxalis bushii Small
Xanthoxalis coloradensis (Rydb.) Rydb.
Xanthoxalis cymosa (Small) Small
Xanthoxalis dillenii (Jacq.) Holub
Xanthoxalis dillenii var. piletocarpa (Wieg.) Holub
Xanthoxalis filipes (Small) Small
Xanthoxalis florida (Salisb.) Moldenke
Xanthoxalis interior Small
Xanthoxalis rufa (Small) Small
Xanthoxalis stricta (L.) Small
Xanthoxalis stricta var. piletocarpa (Wieg.) Moldenke
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name of common
yellow oxalis is Oxalis stricta L. There is considerable debate concerning
all the "yellow" wood oxalis (or sorrels). The Atlas of Virginia Flora lists
four species of Oxalis occurring in Fauquier County: 1) Oxalis florida
Salisbury ssp. florida, 2) Oxalis fontana L. var. fontana, 3) Oxalis stricta
L., and 4) Oxalis violacea L. Three of the four are "yellow" oxalis (Oxalis
violacea being the only non-yellow species in Fauquier County); however,
the U.S.D.A. Natural Resources Conservation Service's PLANTS database
lists Oxalis stricta and Oxalis fontana as the same species (Oxalis stricta,
preferred name;=Oxalis fontana as synonym), while some authorities
recognize another species of wood sorrel, Oxalis dillenii, which also has
yellow flowers and is very similar to Oxalis stricta. The former species is
supposed to have more erect pedicels, rhizomes, and other slightly different
traits that distinguish it from Oxalis stricta. However, it seems more likely
that these are merely variations of the same species. For the Nature Guide,
Oxalis stricta will be the preferred choice and will represent all the "yellow"
wood oxalis inhabitating Sky Meadows State Park.
NATIVE STATUS: Native, United States; Introduced, Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: This native perennial plant is usually about 6" tall, but sometimes
reaches 1' or a little more. There is a central stem that branches occasion-
ally, creating a bushy effect on mature plants. It is often covered with
scattered white hairs.
Leaves: The alternate trifoliate leaves have fairly long petioles, and are
about ¾" across when fully open. Depending on environmental conditions,
they are light green, green, or reddish green, and fold up at night. Occasion-
ally, they fold up in response to intense sunlight during midday.
Flowers: Floppy umbels of yellow flowers emerge from the leaf axils on
long, slightly hairy stalks. Each bell- shaped flower is about ½" across when
fully open, and has 5 petals that flare outward. There are fine lines toward
the throat of the flower, which is subtended by 5 green triangular sepals.
Some- times, the throat of the flower is slightly red. Like the leaves, the
flowers close-up at night. There is little or no floral scent.
Fruit/Seeds: The flowers are replaced by seed capsules about 8-20 mm. long that are cylindrical in shape and 5-sided; their apices are beak-shaped. Immature capsules are light green and their sides are covered with either short appressed hairs or a combination of short appressed hairs and long spreading hairs. At this time, the pedicels become sharply reflexed, bending slightly to moderately downward at their bases, and then bending sharply upward near the bases of the seed capsules to hold them erect. As the capsules continue to mature, they split open into 5 parts to eject their seeds up to several feet away from the mother plants. The small seeds are about 1.0-1.5 mm. long, reddish brown to brown, broadly ellipsoid in shape, and somewhat flattened; they have several transverse ridges that are often whitened.
Roots: The root system consists of a slender branching taproot with num-
erous secondary roots.
REGENERATION PROCESS: Common yellow oxalis spreads by
means of mechanical ejection of the seeds from the slightly hairy elong-
ated seed capsules; each capsule splits into 5 sections.
HABITAT TYPES: Habitats include mesic black soil prairies, openings
in woodlands, savannas, limestone glades, pastures, lawns and gardens,
powerline clearances, edges of paths and driveways, and miscellaneous
waste areas. This plant is more common in degraded habitats.
SITE CHARACTERISTICS: Common yellow oxalis prefers full or
partial sun, and moist to slightly dry conditions. Growth is best in a rich
loamy soil, although poor soil containing clay, gravel, or sand is tolerated.
Common yellow oxalis is a very robust little plant and will spread, if it is
given half a chance, particularly in open, disturbed situations. It doesn't
compete well against taller plants, however.
SEASONAL DEVELOPMENT: The blooming period peaks during late
spring or early summer, but continues intermittently until the fall. Plants
often become dormant during the hot dry spells of mid- to late summer.
GENERAL DISTRIBUTION: The "yellow" wood oxalis, depending on
exactly how this species complex is defined, is found throughout most of
the United States (some far western Rocky Mountain states being
problematic) and Canada.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: Flower visitors include small bees, Syrphid
bee flies, small butterflies, and skippers. Among these insects, bees are
probably the most important pollinators, including such species as Ceratina
dupla dupla (little carpenter bee), Calliopsis andreniformis (andrenid dagger
bee), and Melissodes bimaculata bimaculata (two-spotted miner bee). The
Syrphid flies feed on pollen and are non-pollinating. Several species of
songbirds and upland gamebirds eat the seeds, including the bobwhite,
mourning dove, horned lark, field sparrow, grasshopper sparrow, Savannah
sparrow, and slate-colored junco (winter only). The cottontail rabbit and
white-tailed deer eat this plant occasionally, even though the leaves are
slightly toxic from oxalic acid.
The leaves can be added to salads in small amounts; they have a slightly