182 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
KEY TO THE GENERA. 
Flowers subtended by an involucre; stamens 9; sheaths 
wanting.........--. 2-22 eee eee eee eee eee eee 1. Ertogonvum (p. 182). 
Flowers not involucrate; stamens 4 to 8; sheaths present. 
Stigmas tufted. 
Sepals 4; stigmas 2; achenes lenticular, winged; 
leaves orbicular-reniform..........-.----. 2. Oxyrta (p. 190). 
Sepals 6; stigmas 3; achenes 3-angled, not winged ; 
leaves not orbicular-reniform, elongated or 
hastate......... eee eee eee ee eee eee eee eeee 3. Rumex (p. 191). 
Stigmas capitate. 
Leaf blades jointed at the base; filaments, at least 
the inner, dilated. 
Herbs; flowers fascicled; sepals not winged... 5. Potyaonum (p. 193). 
Shrub; flowers solitary; inner sepals winged.. 4. Gonopryrum (p. 193). 
Leaf blades not jointed at the base; sheaths not 
2-lobed; filaments slender. 
Sheaths cylindric, truncate...............-- 6. Perstcaria (p. 195). 
Sheaths oblique, more or less open on the side 
facing the leaf. 
Sepals, at least the outer ones, keeled or, 
winged; stems twining...........- 8. BrpERDYKIA (p. 197). 
Sepals neither keeled nor winged; stems 
erect. 
Perennials with fleshy rootstocks, 
mostly basal leaves, and 
simple stems.......-...-.-.-- 7. Brstorta (p. 197). 
Annual with fibrous roots, cauline 
leaves, and branched stems.. 9. Fagoryrum (p. 197). 
1. ERIOGONUM Michx. 
Low annuals or perennials, herbaceous, or somewhat woody at the base; leaves 
entire, basal or scattered along the stem; inflorescence various; flowers involucrate; 
involucre 4 to 8-toothed or lobed, mostly many-flowered; calyx with 6 divisions 
(valves), colored, corolla-like; stamens 9; achenes triangular, sometimes winged. 
The genus is one of the largest in our State. Representatives are found almost 
everywhere, especially at lower elevations. Strangely enough, although among our 
commonest plants, no common name seems to have been given them, probably because 
the plants are usually small and inconspicuous. Some species, however, are rather 
handsome. 
KEY TO THE. SPECIES. 
Fruit winged, at least above; large coarse perennials. 
Wings extending the entire length of the fruit; perianth 
glabrous. 
Involucres strigose.....----------- eee eee eee eee eee eee 1. #. alatum. 
Involucres glabrous......-.--..-+-----+-eeeee eee neers 2. E. triste. 
Fruit winged only above the middle; perianth pubescent. 
Leaves loosely and coarsely tomentose beneath, com- 
monly acutish; involucres 3 to 5 mm, long........ 3. E. hieracifolium. 
Leaves very densely and finely tomentose beneath, 
rounded-obtuse; involucres 2 to 3 mm. long...... 4, E. pannosum. 
