1907] Hall. Compositae of Southern California. 215 



88. ARTEMISIA L. WORMWOOD. 



Herbs or shrubby plants, mostly bitter and aromatic, with 

 alternate leaves. Heads small, discoid, nodding or erect, in pan- 

 icled spikes or racemes. Flowers yellow or purplish, all tubular ; 

 disk-flowers perfect and marginal ones pistillate, or all perfect. 

 Corolla of the pistillate flowers 2 or 3-toothed, of the perfect 

 flowers 5-toothed. Involucre imbricated, dry and scarious. Re- 

 ceptacle nearly flat to hemispheric, naked in all our species ex- 

 cept the last. Achenes obovoid or oblong, glabrous (except in 

 A. Parishii), with a small terminal areola. Pappus none. 



Flowers of the margin pistillate; central flowers perfect (their achenes abor- 

 tive and sterile in no. 1). 

 Herbage glabrous. 



Leaves linear, mostly entire 2. A. dracunculoides. 



Leaves serrulate to bipinnatifid 4. A. biennis. 



Herbage (at least the lower surface of the leaves) tomentose. 



Branches spinescent: flowers cobwebby with crisped hairs 



1. A. spinescens. 



Branches not spinescent: flowers resinous. 



Shrubby: leaves or their segments linear-filiform 



3. A. Calif ornica. 



Herbaceous (except at base in some) : leaves or their segments 

 broader. 



Leaves w T hite-tomentose on both sides 5. A. Ludoviciana. 



Leaves green and early glabrate above 6. A. heterophylla. 



Flowers all perfect and fertile: shrubs. 



Eeceptacle naked: leaves white-tomentose or canescent on both sides. 

 Achenes glabrous. 



Accessory bracts of the involucre short and ovate: leaves 3- 



toothed to entire 7. A. tridentata. 



Accessory bracts of the involucre oblong or lanceolate: leaves 



3-cleft or -parted to entire 8. A. trifida. 



Achenes arachnoid with long hairs: leaves mostly entire 



9. A. Parishii. 



Eeceptacle chaffy, most of the flowers being subtended by scale-like 

 bracts: leaves green above 10. A. Palmeri. 



1. A. spinescens Eat., Bot. King Exped. 180, t. 19, ff. 15 to 



21 (1871). Picrothamnus desertorum Nutt., Trans. Am. Philos. 

 Soc. ser. 2, vii. 417 (1841) ; not Artemisia desertorum Spreng. 



(1825-8). 



