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FNA | Family List | FNA Vol. 8 | Saxifragaceae

6. Lithophragma (Nuttall) Torrey & A. Gray, Fl. N. Amer. 1: 583. 1840.

Woodland-star [Greek lithos, stone, and phragma, hedge or fence, alluding to rocky habitat; or an unsuccessful attempt to render Saxifraga in Greek]

Roy L. Taylor

Tellima R. Brown [unranked] Lithophragma Nuttall, J. Acad. Nat. Sci. Philadelphia 7: 26. 1834 (as Lithofragma); Pleurendotria Rafinesque, name rejected

Herbs, rhizomatous, not stoloniferous; caudex sometimes bearing bulbils. Flowering stems erect, leafy, 8-85 cm, stipitate-glandular. Leaves in basal rosette and cauline; cauline leaves (1-)2(-10), usually alternate (opposite in L. cymbalaria), unlobed, lobed, or palmately compound, sometimes with bulbils in axils; stipules present; petiole stipitate-glandular; blade rhombic or orbiculate to reniform, lobed, base cordate, hastate, rounded, ligulate, or cuneate, ultimate margins entire or toothed, apex obtuse or acute, surfaces often stipitate-glandular; venation palmate. Inflorescences compact or lax racemes, arising from axillary buds in basal rosette, 2-12(-25)-flowered, sometimes flowers solitary, (flowers sometimes replaced by bulbils), bracteate. Flowers: hypanthium partially adnate to proximal 1/2 to entire length of ovary, free from ovary 1-2 mm, green; sepals 5, green tinged with red; petals 5, white or pink; nectariferous tissue inconspicuous; stamens 10, (inserted on hypanthium, inner whorl attached proximal to point of petal insertion); filaments filiform; (anthers cordate); pistil 3-carpellate; ovary superior to 1/2 or almost completely inferior, 1-locular, carpels fully connate at ovaries; placentation parietal; styles 3; stigmas 3. Capsules 3-beaked. Seeds (50-200), usually dark brown, ovoid, smooth, wrinkled, or tuberculate. x = 7.

Species 10 (10 in the flora): w North America.

SELECTED REFERENCES Kuzoff, R. K., L. Hufford, and D. E. Soltis. 2001. Structural homology and developmental transformations associated with ovary diversification in Lithophragma (Saxifragaceae). Amer. J. Bot. 88: 196-205. Kuzoff, R. K., D. E. Soltis, L. Hufford, and P. S. Soltis. 1999. Phylogenetic relationships within Lithophragma (Saxifragaceae): Hybridization, allopolyploidy, and ovary diversification. Syst. Bot. 24: 598-615. Taylor, R. L. 1965. The genus Lithophragma (Saxifragaceae). Univ. Calif. Publ. Bot. 37: 1-122.

1 Leaves palmately compound, 3-foliolate; seeds spiny.   1 Lithophragma maximum
+ Leaves unlobed or lobed, or 3-foliolate; seeds smooth, wrinkled, tuberculate, or rough   (2)
2 (1) Stigma papillae in narrow subapical band; seeds smooth or wrinkled   (3)
+ Stigma papillae covering apical surface; seeds tuberculate, tubercles in 3-19 rows, blunt or spinelike   (6)
3 (2) Leaf blades light green; cauline leaves 3-lobed, appearing pinnatifid; flowers persistent, slightly pendulous; racemes erect; petals 5-7-lobed; ovaries to 1/2 inferior.   2 Lithophragma tenellum
+ Leaf blades dark green or reddish green; cauline leaves 3-foliolate or 3-lobed; flowers deciduous if unfertilized, horizontal; racemes often lax, nodding; petals 3-lobed; ovaries 1/2+ inferior   (4)
4 (3) Hypanthia elongate-obconic, length 3-4 times diam.; petals pink; flowers fragrant.   3 Lithophragma trifoliatum
+ Hypanthia obconic to obconic-elongate, length 2 times diam.; petals usually white, sometimes pink; flowers not fragrant   (5)
5 (4) Cauline leaves 3-foliolate; hypanthia obconic-elongate; petals white or pink, often with prominent venation, 3-lobed, obovate-rhombic, widely spreading, ultimate margins entire; ovaries 1/2+ inferior.   4 Lithophragma parviflorum
+ Cauline leaves 3-lobed; hypanthia obconic; petals white with obscure venation, usually shallowly 3-lobed, ovate-elliptic, not widely spreading, ultimate margins sometimes with extra tooth, (lobes acute); ovaries ± completely inferior.   5 Lithophragma affine
6 (2) Cauline leaves opposite (1 pair); flowering stems simple; petals unlobed, without serrations at base, ultimate margins entire.   6 Lithophragma cymbalaria
+ Cauline leaves alternate; flowering stems often branched; petals lobed or, if unlobed, margins sometimes with serrations at base   (7)
7 (6) Hypanthia broadly campanulate; flowers pendulous, petals partly included, ovate-elliptic, ultimate margins lacerate; flowers ± sessile.   7 Lithophragma campanulatum
+ Hypanthia narrowly campanulate; flowers horizontal, petals completely exserted, obovate-pandurate, ovate-elliptic, or ovate and palmately 5-lobed, ultimate margins entire; flowers long-pedicellate   (8)
8 (7) Hypanthia with truncate base; petals white, simple or 3-7-lobed; flowers not fragrant; racemes lax, nodding; cauline leaves 2-10; ovaries superior.   8 Lithophragma heterophyllum
+ Hypanthia with acute, obtuse, or hemispheric base; petals white or pink, unlobed, serrately 3-5-lobed, or 5-lobed; flowers sometimes fragrant; racemes erect; cauline leaves 2-4; ovaries to 1/2 inferior   (9)
9 (8) Plants usually robust; leaves usually unlobed or 3-5-lobed; petals white, unlobed or 3-5-lobed with serrations at base; inflorescences 2(-3)-branched, 3-5(-25)-flowered racemes, flowers rarely replaced with bulbils.   9 Lithophragma bolanderi
+ Plants usually fragile; leaves lobed (lobes rounded); petals usually pink, rarely white, palmately 5-lobed, base without serrations; inflorescences rarely branched (unless plant with bulbils), solitary flowers or 2-5(-7)-flowered racemes, often appearing corymbose; flowers sometimes replaced with bulbils.   10 Lithophragma glabrum

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