FAMILIES OF PLANTS 
135 
Groundsel (Senecio) 'The groundsels are herbaceous plants with 
alternate leaves and heads of yellow flowers, both ray and disk. The 
bracts of the involucre are in one series and all about equal in length, 
but sometimes there are one or two rows of outer, extra bracts at the 
base. The receptacle is flat and there are no chaffy bracts between 
the flowers. The pappus consists of an abundance of soft, white 
hairs. Fifteen species have been identified in the park, and these 
may be distinguished by 
means of the following key: 
1. Leaves or some of them pin¬ 
nate or pinnately lobed. 2. 
1. Leaves not at all pinnate or 
pinnately lobed. 7. 
2. Heads usually solitary. 
Senecio subnudus. 
2. Heads several. 3. 
3. Leaves fleshy-thickened. 
Senecio cymbalarioides. 
3. Leaves not fleshy-thick¬ 
ened. 4. 
4. Plants usually less than a 
foot high. Senecia muta- 
bilis. 
4. Plants usually more than a 
foot high. 5. 
5. Rays yellow. Senecio bal- 
samitae. 
5. Rays orange. 6. 
6. Basal leaves larger than the 
others. Senecio pseudau- 
reus. 
6. Basal leaves small and soon withering. Senecio longipetiolatus. 
7. Stems nearly equably leafy to the top. 8. 
7. Stems few-leaved or with the upper leaves reduced in size. 11. 
8. At least some of the leaves triangular in shape. Arrowleaf butterweed 
(Senecio triangularis). 
8. None of the leaves triangular in shape. 9. 
9. Leaves entire or nearly so. Senecio crassulus. 
9. Leaves toothed. 10. 
10. Stems more than 2 feet high. Serra butterweed ( Senecio serra). 
10. Stems less than a foot high. Senecio fremontii. 
11. Stems more than 2 feet high. Senecio hgdrophilus. 
11. Stems less than 2 feet high. 12. 
12. Leaves entire or nearly so. 13. 
12. Leaves toothed. 14. 
13. Plant smooth or nearly so. Bracts of the involucre with conspicuous black 
tips. Senecio glaucescens. 
13. Plant densely white-woolly. Bracts of the involucre without black tips. 
Woolly groundsel ( Senecio canus). 
14. Plants less than 2 feet high. Senecio perplexus. 
14. Plants usually more than 2 feet high. Senecio altus. 
Figure 113. —Arrowleaf butterweed. Yellow. Pho¬ 
tograph by Dr. Harvey E. Stork. 
