COMPOSITAE (COMPOSITE FAMILY) 565 



83. CHRYSANTHEMUM L. OXEYE DAISY 



Perennial herbs, with toothed, pinnatifid, or divided leaves, and single or 

 corymbed heads. Heads many-flowered; rays white, numerous, fertile. 

 Bracts of the broad and flat involucre imbricated, with scarious margins. 

 Receptacle flat or convex, naked. Disk-corollas with a flattened tube. Achene 

 of disk and ray similar, striate, without pappus. 



1. Chrysanthemum Leucanthemum L. Sp. PL 888. 1753. Glabrous, 3-6 

 dm. high, simple or sparingly branched: cauline leaves spatulate, and the 

 upper gradually narrower, becoming small and linear, pinnately dentate or 

 incised, partly clasping at base; the radical broader, petioled: head broad and 

 flat: rays about 2.5 cm. long. Becoming naturalized about Denver, and 

 probably elsewhere in our range; of European origin but common in the 

 eastern United States. 



84. TANACETUM L. 



Herbs or suffruticose plants with alternate variously dissected leaves and 

 solitary or corymbose heads of yellow flowers. Heads many-flowered, discoid; 

 the flowers all tubular and perfect, with 3-5-toothed corolla, or the marginal 

 ones pistillate with more or less oblique or imperfectly ligulate corolla. Bracts 

 of the involucre imbricated, in few or several ranks. Styles deciduous. 

 Achenes 5-ribbed or 3-5-angled, with broad truncate summit bearing a 

 coroniform pappus or none. Sphaeromeria Nutt. as to our species. The com- 

 mon garden TANSY may occur as an escape from gardens. 



Leaves linear and simple or nearly so 1. T. simplex. 



Leaves 3-5-cleft. 



Leaves cleft into linear lobes . . . . . . . . 2. T. capitatum. 



Leaves broadly cuneate and obtusely 3-5-lobed 3. T. Nuttallii. 



1. Tanacetum simplex A. Nels. Bull. Tor. Bot.Club26: 484. 1899. Caudex 

 of few short crowded branches, the crowns scarcely above the surface of the 

 ground: leaves crowded on the crowns, closely and finely appressed-silvery- 

 canescent, erect, mostly simple and linear, a few bifid or trifid at the apex, only 

 2-3 cm. long: stems few, rising singly from the crowns, slender, 6-12 cm. high, 

 bearing 2-3 small linear leaves and a single head: head 6-8 mm. high, many- 

 flowered; involucral bracts oval to obovate, in two rows, with slightly thick- 

 ened greenish midrib and scarious margins: corolla-tubes thin and somewhat 

 transparent: the pistillate flowers in one series: achenes oblong, or slightly 

 enlarged upward, obtuse. On stony hillsides; southern Wyoming. 



2. Tanacetum capitatum (Nutt.) T. & G. Fl. 2: 415. 1842. Silyery- 

 canescent, densely caespitose: leaves simple or pedately 3-5-parted into linear 

 lobes: flowering stems scapiform or 2-4-leayed: heads 10 or more, sessile in a 

 globose glomerule. Frequent on barren arid hills; Wyoming and in adjacent 

 Utah, Idaho, and Montana. 



3. Tanacetum Nuttallii T. & G. 1. c. Silvery-canescent, loosely caespitose, 

 10-15 cm. high: leaves short, mostly broad-cuneate with tapering base, ob- 

 tusely 3-5-lobed at the broad summit; those of the flowering stems usually 

 oblong or linear and entire : heads few, somewhat paniculate or loosely clus- 

 tered, some of them slender-pedunculate: involucre very scarious. Dry hills; 

 same range as the preceding. 



85. ARTEMISIA L. SAGEBRUSH. WORMWOOD. 



Bitter aromatic herbs or shrubs with alternate leaves and small, paniculately 

 disposed, commonly nodding heads of yellow or whitish flowers. Heads few to 

 many-flowered, small, wholly discoid; heterogamous, the pistillate flowers with 

 small and slender tubular corolla, and the hermaphrodite either sterile or 

 fertile; or homogamous, with the flowers all hermaphrodite and fertile. In- 

 volucre imbricated hi few or several rows. Anthers commonly tipped with 



