FAMILIES OF PLANTS 
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those on the stem are sessile while the basal ones are petioled. The 
heads are broad and flat with yellow disk flowers and white ray 
flowers, about an inch long. There is no pappus. 
Wormwood and Sagebrush (Artemisia) .—The various species of 
Artemisia are, in most cases, very aromatic and have alternate leaves 
and small, inconspicuous heads of yellow or yellowish-white disk 
flowers. There are no ray flowers and the disk flowers have no pap¬ 
pus. The bracts of the involucre are in several series. The herba¬ 
ceous species are called wormwood and the woody ones are called 
sagebrush. The species found in the park may be distinguished 
by means of the following key: 
1. Shrubs. 2. 
1. Herbs. 4. 
2. Leaves linear and entire or nearly so. Siver sagebrush ( Artemisia cana). 
2. Leaves cleft into 3 long, linear segments. Artemisia trifida. 
2. Leaves 3-toothed or lobed at the apex. 3. 
3. Plants dwarf, usually less than a foot high. Low sagebrush ( Artemisia 
art)uscula). 
3. Plants usually more than a foot high. Big sagebrush ( Artemisia triden - 
tata). 
4. Leaves entire or the lower somewhat toothed or lobed. 5. 
4. Leaves once or twice pinnately or ternately divided. 7. 
5. Plant dark green and smooth. False tarrogon ( Artemisia aromatica) . 
5. Plant white or silvery hairy. 6. 
6. Heads small and numerous. Cudweed sagebrush ( Artemisia gnaphalodes ). 
6. Heads one-fourth inch or more in diameter and few. Artemisia paiicicephala. 
7. Stems smooth or nearly so. 8. 
7. Stems silky-hairy. 9. 
8. Foliage with odor of sage. Artemisia canadensis. 
8. Foliage without odor. Artemisia biennis. 
9. Heads large, one-fourth to one-half inch broad, and few. Artemisia scopu- 
lorum. 
9. Heads small, one-fifth of an inch or less broad. 10. 
10. Plants dwarf, 2 to 5 inches high. Artemisia pedatifida. 
10. Plants 8 to 12 inches high. Fringed wormwood ( Artemisia frigida). 
In addition to the above species Sagebrush (Artemisia discolor) 
and A. sub glabra have also been reported as occurring in the park. 
Arnica (Arnica). —The arnica is an herb with opposite leaves and 
comparatively large heads of yellow flow r ers. All but one species 
found in the park have conspicuous ray flowers. The pappus con¬ 
sists of rather numerous, rigid, hairlike bristles. Ten species have 
been identified in the park and they are distinguished as follows: 
1. Heads without ray flowers. Arnica parryi. 
1. Heads with ray flowers. 2. 
2. At least some of the leaves with heart-shaped base. 3. 
2. None of the leaves with heart-shaped base. 6. 
3. Plants usually less than a foot high. 4. 
3. Plants usually more than a foot high. 5. 
4. Leaves smooth. Arnica gracilis. 
