Oppositeleaf Lewisia

Lewisia oppositifolia is known only from Del Norte County, California, and Josephine County, Oregon.

The floral symmetry of Lewisia oppositifolia may be somewhat elliptical, the outer two petals alternating with the sepals and the remaining petals imbricate and opposite the sepals, giving the flowers a pinched appearance, a feature also reported for L. nevadensis. The more diminutive, higher-elevation plants of L. oppositifolia possibly represent a distinct taxon that has been informally recognized as "Lewisia richeyi" (B. Mathew 1989b).

Taproots gradually ramified distally. Stems erect, basal nodes underground, 10-20(-25) cm. Leaves: basal leaves withering at or soon after anthesis, abruptly narrowed into broad petiole, blade linear-spatulate to linear-oblanceolate, flattened, 4-11 cm, margins entire, apex obtuse to subacute; cauline leaves opposite, in 1-3 pairs near stem base, smaller than and similar to basal leaves. Inflorescences racemose to subumbellate cymes, (1-)2-5(-6)-flowered; bracts alternate proximally, 1-many at each flowering node distally, lanceolate, 4-8 mm, margins entire or toothed at apex, apex acute to acuminate. Flowers pedicellate, not disarticulate in fruit; sepals 2, suborbiculate, 4-8(-10) mm, herbaceous at anthesis, margins coarsely toothed but not glandular, apex obtuse to rounded; petals 8-11, pink fading to white, oblanceolate to obovate, 9-15 mm; stamens 8-18; stigmas 3-5; pedicel 20-75 mm. Capsules 5-6 mm. Seeds 5-15, 1-1.8 mm, shiny, smooth.

Calif., Oreg.

Flowering spring.

Decomposed serpentine substrates; 300-1300m.

Calandrinia oppositifolia S. Watson, Proc. Amer. Acad. Arts 20: 355. 1885; Oreobroma oppositifolium (S. Watson) Howell

Oreobroma oppositifolium (S. Wats.) Howell, Erythea 1 : 32
1893.
Calandrinia oppositifolia S. Wats. Proc. Am. Acad. 20: 355. 1885.
Lewisia oppositifolia B. L. Robinson, in A. Gray, Syn. Fl. N. Am. I 1 : 268. 1897.
Perennial, with a thick taproot and short caudex; basal leaves linear-oblanceolate, 4—10 cm. long, 5-10 mm. wide, the blade decurrent on the short scarious-winged petiole; scape or stem 1-2 dm. high, 1-4-flowered; lower stem-leaves opposite, similar to the basal leaves but smaller, the upper alternate, bract-like, lanceolate, about 5 mm. long; inflorescence racemiform or corymbiform; pedicels 2-4 cm. long; sepals orbicular, 6-8 mm. long, dentate along the rounded apex; petals 10, oblanceolate, denticulate at the apex, white or pinkish, 10-12 mm. long; stamens 8-12; stigmas 3; capsule oblong-ovoid, 6 mm. long, 5-10-seeded; seeds smooth, shining.
Type locality: Waldo, Oregon.
Distribution: Coast mountains of southern Oregon and northern California.

Lewisia oppositifolia is a rare species of flowering plant in the family Montiaceae known by the common name opposite-leaf lewisia. It is native to the Klamath Mountains of Josephine County, Oregon, and Del Norte County, California, where it is a local serpentine endemic generally found in moist areas. This is a perennial herb growing from a small taproot and caudex unit. It produces a basal rosette of several lance-shaped, blunt-tipped fleshy leaves up to 11 centimeters long. There are sometimes smaller leaves located on the lower stem. The inflorescence is made up of one or more erect stems up to about 20 centimeters long, each bearing 1 to 6 flowers. The flower has 8 to 11 white to pale pink petals with blunt or jagged tips, each between 1 and 2 centimeters long. At the center are several stamens with pale anthers. This plant has a limited distribution and it is threatened by human activity in the area, such as logging.