230 OXALIDACEAE. 



302. OXALIS^ WOOD SORREL. 



Annual or perennial, short-stemmed or stemless herbs with 

 alternate or basal trifoliolate leaves (in ours) and axillary or 

 basal 1 -several-flowered peduncles, sometimes also with small 

 self-pollinating flowers; styles 5, separate, persistent; capsule 

 subglobose, ovoid or columnar. 



Caulescent ; flowers yellow. 0. suksdorfii. 

 Acaulescent; flowers white. 



Scapes 1-flowered; capsule ovoid. 0. oregana. 



Scapes several-flowered; capsule linear. 0. trittiifolia. 



Oxalis suksdorfii Trelease. (0. pumila Nutt. not Urv.) Rootstocks 

 creeping; stems slender, 10-30 cm. high, sparsely villous; leaflets obcordate, 

 10-15 mm. long; stipules wanting; peduncles about as long as the subtending 

 leaf; flowers yellow, solitary or in pairs on slender pedicels; sepals oblong, 

 villous; petals three times as long as the sepals, obtuse; capsule a little longer 

 than the sepals. 



In dry open woods, Clarke County, Washington, and southwards. 



Oxalis oregana Nutt. Acaulescent, sparsely villous; petioles 5-20 cm. 

 long; leaflets obcordate, 2-4 cm. long, glabrous above; scapes shorter than the 

 leaves, 2-bracted above the middle; flower solitary; sepals oblong; petals white 

 with purple veins, oblong, 15-25 mm. long; capsule subglobose, 10 mm. long. 



In deep woods, especially at low altitudes in the mountains. 



Oxalis trilliifolia Hook. Acaulescent, nearly glabrous; petioles 10-30 

 cm. long; leaflets 3-5 cm. long, broadly obcordate; scapes as long as the leaves; 

 umbels 3-8-flowered; bracts lanceolate, acute; sepals ovate-lanceolate, acute, 

 4 mm. long; petals white, oblanceolate, deeply notched and twice as long as 

 the sepals; capsule linear, 2-3 cm. long. 



In deep woods, often growing with 0. oregana. 



Family 53. EUPHORBIACEAE. SPURGE FAMILY. 



Herbs (in ours), with milky juice; leaves opposite, alternate or 

 whorled, entire or toothed, sessile or petioled; stipules present 

 or wanting; flowers monoecious or dioecious, often much reduced 

 and subtended by an involucre which resembles a calyx; parts of 

 flowers various, often different in staminate and pistillate flowers; 

 calyx none or minute; petals often wanting; stamens 1-many, 

 free or united; ovary usually 3-celled; fruit a 3-lobed capsule; 

 endosperm copious. 



Flowers surrounded by an involucre; capsule 3-celled. 303. EUPHORBIA, 230. 

 Flowers without an involucre; capsule 1-celled. 304. PISCARIA, 231. 



303. EUPHORBIA. SPURGE. 



Perennial or annual herbs (in ours); flowers monoecious, in- 

 cluded in a cup-shaped 4- or 5-lobed involucre resembling a calyx 

 or corolla and usually bearing large thick glands at its sinuses; 



