372 Compositaceae 
HOWELLIA 
Annual, aquatic, |—5 dm. high. Leaves alternate, submerged ones linear-setaceous 
and entire, emersed ones linear to oblong and sometimes slightly toothed. Flowers of 2 
forms; submerged ones apetalous, axillary, short-peduncled. Calyx-tube slender; lobes 
nearly equal, narrow, 4—8 mm. long. Corolla 4—8 mm. long, white; tube short, split 
nearly to base; limb nearly equally 5-lobed. Stamen tube nearly free; 2 smaller anthers 
each with 3 hairs. Ovary 1|-celled. Capsule membranous, about 12 mm. long, long 
club-shaped, bursting irregularly on one side. Seeds few, large, smooth, white. (Honor 
of J. and T. Howell, Oregon botanists.) W. 
H. aquatilis Gray 
COMPOSITACEAE (Compositae) Composite Family 
Herbs or shrubs or trees (not ours). Leaves various in form and arrangement. 
Flowers in heads, often of 2 kinds, their parts in 4’s or 5’s; heads involucrate. Calxy- 
limb none or cup-like, or of teeth or scales or awns or capillary bristles, often serving as 
a means of seed-dispersal. Corolla on the calyx, tubular or strap-shaped, or the inner 
tubular (disk-flowers) and the outer strap-shaped (ray-flowers). Stamens as many as 
corolla-lobes, alternate with them, on the corolla-tube; anthers syngenesious. Ovary 
l-celled, ovule |; style 1, stigmas 2 in fertile flowers. Fruit an akene. 
A plant may be traced to its tribe by the scientific key immediately following, or by 
the artificial key on page 373, or by both.* 
Scientific Key to the Tribes 
A. Corolla all tubular and regular, or only the marginal ones ligulate. 
B. Heads rayless or radiate; anther not tailed at base; style-branches either truncate 
or tipped with an appendage. 
C. Heads rayless; flowers never yellow, all perfect; style-branches clavate. 
: EUPATOREAE (p. 374) 
CC. Heads usually radiate, very rarely both rayless and yellow; style-branches 
rarely clavate. 
D.  Style-branches of the perfect flowers either flat or tipped with a distinct 
appendage; leaves mostly alternate. ASTEREAE (p. 375) 
DD. Style branches of the perfect flowers truncate or appendaged but not flat- 
tened; leaves often opposite. 
E. Involucre not scarious. 
F. Pappus none or not capillary. 
G. Receptacle chaffy. HELIANTHEAE (p. 395) 
GG. Receptacle chafly except in Gaillardia. HELENEAE (p. 404) 
FF. Pappus capillary; receptacle not chaffy. SENECEAE (p. 411) 
EE. Involucre scarious; pappus none or not capillary; receptacle not chaffy 
except in Anthemis and Achillea. ANTHEMEAE (p. 407) 
BB. Heads rayless except /nula; anthers tailed at base; style-branches neither trun- 
cate nor tipped with an appendage. 
H. Corollas not deeply cleft; receptacle not bristly except Evax. 
HH. Corolls deeply cleft; receptacle bristly. CYNAREAE (p. 417) 
AA. Corolls all ligulate, all perfect. CICHOREAE (p. 420) 

*The artificial key is an attempt to reach the tribes without using the style-branches 
and the anther-bases, two points at which the student very often has trouble. 

