8 OXALIDACEAE 



Family 72. OXALIDACEAE. 



Wood-sorrel Family. 



Annual or perennial, leafy-stemmed or acaulescent herbs, often with rootstocks 

 or scaly bulbs, with sour sap (oxalic acid), and mostly palmately 3-foliolate leaves. 

 Stipules commonly present as scarious margins to the bases of the petioles ; leaflets 

 mostly obcordate. Flowers perfect, in umbel-like or forking cymes or rarely solitary, 

 on mostly rather long peduncles. Sepals 5, often unequal. Petals 5, white, purple, or 

 yellow. Stamens 10-15. Ovary 5-lobed, 5-celled; styles united or distinct; ovules 

 2 to many in each cell. Fruit a loculicidal, globose or columnar capsule. Embryo 

 straight ; endosperm fleshy. 



A family of 7 genera and about 330 species, chiefly in tropical regions. 



1. OXALIS L. Sp. PI. 433. 1753. 



Perennial caulescent or acaulescent herbs, from taproots, rootstocks or bulbs. Leaves 

 alternate, usually with elongated petioles, trifoliolate; leaflets mostly obcordate, notched at 

 the apex. Flowers on axillary or scape-like peduncles, sepals and petals 5; stamens 10. 

 Seeds few to many in each cell, variously wrinkled, grooved, pitted or striate. [Name 

 Greek, meaning sour, from the acid juice.] 



A genus of about 300 species, mainly in warm temperate and tropical regions. Type species, Oxalis Aceto- 

 sella L. 



Flowers white or purple. 



Cyme 1-flowered, subtended by 1 or 2 clasping bracts. 1. O. oregana. 



Cyme several-flowered, umbel-like, subtended by a whorl of narrow bracts. 2. O. trilliifolia. 



Flowers yellow. 



Plants acaulescent; rootstocks bearing bulblets; petals 20 mm. long. 3. 0. cernua. 



Plants caulescent; rootstocks not producing bulblets; petals less than 20 mm. long. 

 Stems arising from slender rootstocks; longer filaments pubescent. 



Petals 4-8 mm. long. 4. O. corniculata. 



Petals 12-18 mm. long. 5. O. Suksdorfii. 



Stems arising from a tufted woody fusiform root; longer filaments glabrous. 



Pedicels with spreading pubescence, shorter than the capsules. 6. O. pilosa. 



Pedicels with appressed pubescence, longer than the capsules. 7. 0. calif ornica. 



1. Oxalis oregana Nutt. Oregon Wood-sorrel. Fig. 2981. 



Oxalis oregana Nutt. in Torr. & Gray, Fl. N. Amer. 1: 211. 1838. 



Oxalis Acetosella var. oregana Trelease, Mem. Bost. Soc. Nat. Hist. 4: 90. 1888. 



Oxys oregana Greene, Man. Bay Reg. 71. 1894. 



Oxalis macra Small, N. Amer. Fl. 25 : 26. 1907. 



Oxalis Smalliana R. Knuth, Notizblatt 7: 308. 1919. 



Oxalis oregana var. Tracyi Jepson, Man. Fl. PI. Calif. 588. 1925. 



Acaulescent perennial from slender creeping rootstocks, more or less rusty-villous. Leaflets 

 broadly obcordate, 2-3 cm. long, on petioles 5-15 cm. long; peduncles scape-like, bearing a single 

 flower ; pedicel subtended by 2 bracts ; petals white or rose-colored, purple-veined, oblong-ovate, 

 15-20 mm. long ; capsule round-ovoid, 7 mm. long. 



Shady woods, Humid Transition and Canadian Zones; western Washington to Monterey County, California. 

 Type locality: "Shady woods of the Oregon [Columbia River] in moist places." Feb.-Sept. Redwood Sorrel. 



2. Oxalis trilliifolia Hook. Trillium-leaved Wood-sorrel. Fig. 2982. 



Oxalis trilliifolia Hook. Fl. Bor. Amer. 1: 118. 1830. 

 Hesperoxalis trilliifolia Small, N. Amer. Fl. 25: 27. 1907. 



Plants acaulescent, arising from stout rootstocks. Leaves with elongated glabrous or nearly 

 glabrous petioles often 2 dm. long ; leaflets broadly obcordate, 25-40 mm. wide, glabrous above, 

 sparsely pubescent beneath ; scapes about as long as the petioles ; cyme umbel-like, 2-8-flowered ; 

 petals white or pink, 8-14 mm. long, deeply notched; capsule glabrous, erect, 25-30 mm. long, 

 slender-fusiform. 



Swamps and margins of streams, Canadian Zone; western Washington and Oregon. Type locality: near the 

 Grand Rapids of the Columbia. June-Aug. Columbia Oxalis. 



3. Oxalis cernua Thunb. Cape OxaHs. Fig. 2983. 



Oxalis cernua Thunb. Diss. Oxalis 14. 1781. 

 Bolboxalis cernua Small, N. Amer. Fl. 25: 28. 1907. 



Acaulescent perennial, somewhat fleshy, bright green, the rootstocks bearing bulblets at the 

 nodes. Leaves basal, with elongated petioles; leaflets broadly obcordate, 20-35 mm. broad, 

 glabrous or sometimes pubescent beneath ; peduncles 1-4 dm. high, 4-20-flowered ; sepals lanceo- 



