180 
BOTANY. 
brandies of the style exserted and slightly recurved ; remaining florets per- 
fect, corolla 5-tootlied, branches of the style included, truncate and with a 
few cilias at the middle of the ends; immature achenia obloug-top-shaped ; 
jiappus none. — With much the appearance of Artetnisia cana^ but the broad- 
topped achenia are characteristic of Tanacetum. Whether this is to be re- 
ferred to the section Sph(Ero7neria or not, must be decided by the examina- 
tion of maturer specimens. Limestone rocks at the mouth of a canon in the 
East Humboldt Mountains, Nevada; 6,500 feet elevation; July. Plate 
XIX. Fig. 8. Portion of a plant ; natural size. Fig. 9. Eeceptacle. Fig. 
10. In volucral scale ; each enlarged four diameters. Fig. 11. Outer pistillate 
fertile flower. Fig. 12. Inner perfect flower ; each enlarged eight diameters. 
Fig. 13. Style of perfect flower. Fig. 14. Stamen ; each enlarged twelve 
diameters. (631.) 
Tanacetum diveesifolium. Suffi-uticose, glabrous, branched from the 
base ; branches 8-15' high, leafy to the top ; leaves 1-2' long, J-1" wide, 
sessile, narrowly linear, 1 -nerved, or pinnatifid with 1-4 hnear-oblong 
1 -nerved divisions ; heads small, sub-globose, congested or laxly disposed in 
tcrtniual corymbs; peduncles and involucres puberulent, the latter cup-shaped, 
of 12-15 oval scarious-margined concave scales ; receptacle conical; florets 
60-70 ; outer pistillate ones 8-10, with a 3-4-lobed corolla a Httle shorter 
tlian the style ; inner perfect ones, 5-lobed branches of the style very mi- 
nutely penicillate at the broad truncate extremities; achenia oblong, crowned 
with a slightly elevated ring.— A dense much-branched plant, shrubby at the 
])aso, 111 habit not unhke some narrow-leaved Linosyris. Central flowers 
\^ itli n rudimentary seed, but possibly infertile. Canons of Cottonwood 
Creek uii.l American Fork, in the Wahsatch; 6,000 feet elevation; July, 
August. Plate XIX. Fig. 1. A single stem; natural size. Fig. 2. Eecep- 
tacle. Fig. 3. Involucral scale ; each enlarged four times. Fig. 4. An 
outer pistillate fertile flower. Fig. 5. An inner perfect flower; each enlarged 
eight times. Fig. 6. Stamen. Fig. 7. Style of inner flower ; each enlarged 
twelve times. (632.) 
Artemisia spinescens. {Picrothamnus desertorum, Nutt.) Low, fru- 
tesccul , densely-branched, white-tomentose ; leaves scarcely 3" long, pedately 
3-5-partcd, the divisions 3-lobed, lobes oblong; heads rather small, globose, 
in short axillary racemes or spikes, the racliis persistent 2-3 years and spin- 
escent ; involucral scales 5-6, obovate, obtuse, concave ; receptacle smaD, 
