132 Polygonaceae 
ored. Fruit ovate, lens-shaped, enclosed in the perianth. (Gk. oxys==sharp, theke= 
case, sac; referring to the pointed anthers.) E. 
0. dendroidea Nutt. 
ERIOGONUM ERIOGONUM 
Herbs or shrubs or shrubby at base, annual or perennial. Stems leafy or none, 
simple or branched, often tufted. Leaves entire, alternate or opposite or whorled. Flow- 
ers in heads or umbels or cymes or fascicles; clusters involucrate; involucre 4—8-toothed 
or -cleft, campanulate or top-shaped or almost cylindric. Perianth 6-cleft or -parted, 
usually colored; segments equal or the outer ones larger. Stamens 9, included or ex- 
serted; filaments filiform, often villous. Style 3-parted; stigmas capitate. Akene pyra- 
midal, 3-angled, more or less swollen near the base, enclosed by the perianth-segments or 
winged. (Gk. erion—wool, gonu=knee; on account of the woolly and jointed stems.) 
A.  Involucre 5—6-veined, often angled. 
B. Annual; leaves all basal, or rarely some on the nodes of the stems. 
C. Leaves oblong; involucre 4 mm. long; plant sparingly branched, tomentose 
thruout. W. C. E. virgatum Benth. 
CC. Leaves orbicular to broadly ovate; involucre |—3 mm. long; plant diffusely 
branched, glabrous or somewhat tomentose thruout. 
D.  Involucre 3 mm. long. E. 
E. vimineum Dougl. 
DD.  Involucre 1—1.5 mm. long. E. 
E. baileyi Wats. 
BB. Perennial; leaves mostly not basal, usually some on the nodes of the stem. 
E.  Perianth-segments all very similar and nearly equal. 
Fgee bterpsi: 
G. Peduncles not fistulous, slender. E. 
E. strictum Benth. 
GG. Peduncles fistulous, stout. 
H. Peduncles 2.5—15 cm. high; heads solitary. 
I. Perianth-segments ovate; leaves linear-oblanceolate, glabrate above. 
Fe E. pauciflorum Pursh 
II. Perianth-segments cuneate; leaves spatulate or oblanceolate, white- 
tomentose on both sides. E. 
E. multiceps Nees 
HH. Peduncles 30—120 cm. high; heads solitary or few. 
J. Leaves acute, 5—15 cm. long; involucre tomentose; flowers white 
or rose. E. KE. elatum Dousgl. 
JJ. Leaves obtuse, 1—5 cm. long; involucre glabrate; flowers yellow 
or reddish. E. 
E. nudum Dougl. 
FF. Shrubs, or shrubby below. 
K. Flowers yellow. E. 
E. campanulatum Nutt. 
KK. Flowers not yellow. 
L. Styles and stamens included. E. (E. microthecum.) 
E. effusum Nutt. 
LL. Styles exserted. E. 
E. corymbosum Benth. 
EE. Outer perianth-segments wider than the inner. 
M. Unmbel simple. 
