AMBROSIA ANTENNARIA 253 



a, Achene 3-4 mm. long, with a thread-like beak 



10-15 mm. long A, grandiflora 



b. Achene 7-12 mm. long, with a short stout beak 



1-4 mm. long A.glauca 



2. Heads orange to purple; achene 6-8 mm. long, 



with a thread-like beak, 5-10 mm. long A. aurantiaca 



AMBROSIA Linne 1753 RAGWEED, KINGHEAD 

 (The Latin name) 



Heads without rays, monoecious, achenes ovoid or obovoid, pappus 

 none, involucre closed, usually with 4-8 tubercles or spines, staminate 

 heads open, many-flowered, corolla present, involucre 5-12-lobed, heads 

 spiked or racemed, pistillate heads 1 -flowered, without corolla, solitary or 

 clustered ; leaves alternate or opposite, lobed or divided ; annual or perennial. 



1. Leaves digitately 3-5-lobed; stems 3-15 ft. high A. trifida 



2. Leaves 1-3-pinnatifid ; stems 1-5 ft. high 



a. Fruiting involucre with 4-6 spines about the 



summit; annual A.artemisifolia 



b. Fruiting involucre spineless or with 3-4 tuber- 



cles ; perennial by rootstocks A. psilostdchya 



ANAPHALIS DeCandolle 1837 PEARLY EVERLASTING 

 (Greek name of some plant) 



Heads without rays, dioecious, staminate and pistillate flowers with 

 corolla and hair-like pappus, achenes oblong; receptacle convex without 

 chaff, involucre oblong to bell-shaped, the bracts papery, pearly white, 

 imbricated in several rows ; heads in corymbs ; leaves alternate, entire, 

 white-woolly ; perennial. 



Stems 1-2 ft. high; leaves 2-5 in. long, lance-linear, 

 green above, woolly below ; heads- 6 mm. high A. margaritdcea 



ANTENNARIA Gaertner 1791 CATSFOOT 



(Latin antenna, feeler) 



PL 38, fig. 2. 



Heads without rays, usually dioecious, staminate and pistillate flowers 

 with hair-like pappus, achenes oblong, round or somewhat flattened; re- 

 ceptacle convex or flat without chaff, involucre oblong to bell-shaped, usu- 

 ally woolly, the bracts papery, imbricated in several rows; heads in dense 

 clusters, corymbs or racemes ; leaves alternate, basal, mostly entire, woolly ; 

 perennial. 



