820 PATAGONIAN EXPEDITIONS I BOTANY. 



Species 2, A. bicolor Hook, in Himalaya, Japan, and N. Amer., and the 

 following. A case of discontinuity. (Fig. in Eng. & Prantl, iv, 5, p. 

 206, G-L.) 



ADENOCAULON CHILENSE Less. (A. lechleri Sch. Bip.) 



Leaves largely oval, rounded or subcordate at their base, slightly 

 toothed, or entire at their margin. 



(Chili) ; Patagon., Chubut; Magellan ; S. Fuegia, at Ushuaia. 



33. PARTHENIUM Linn. 



Mostly hairy, or hoary herbs or shrubs, with alternate leaves, and small 

 corymbose heads of both tubular and radiate, white or yellow flowers. 

 Involucre broad, its scales 2-3-seriate, appressed, subequal. Chaff sur- 

 rounding the disk-flowers. Ray-flowers about 5, their ligules short, 2- 

 lobed. Disk-flowers sterile. Anthers basi-entire. Achenes compressed, 

 bearing the persistent rays and pappus of 23 awns. 



Species 10, N. Amer. to northern part of S. Amer. 



P. HYSTEROPHORUS Linn. 



Herbaceous annual, hispid below, hoary at top. Leaves variously 

 bipinnatipartite. Involucral scales acute. Papptis-scales oval-oblong, 

 obtuse, membranaceous. (Fig. in Eng. & Prantl, iv, 5, p. 114, M, N.) 



(Tex., by Mexico and W. Indies to S. Amer.; also Mauritius.) N. 

 Patagon., near Rio Negro. 



34. AMBROSIA Linn. American Ragweed. 



Monoecious or dioecious branching herbs or shrubs, with small heads of 

 green flowers, the staminate in spikes or racemes, the pistillate solitary or 

 few in the axils. Pistillate heads i -flowered, with 4-8 spines, without 

 petals or pappus. Staminate heads many-flowered, often with filiform 

 chaff, scarcely synantherous. (Flowers so far reduced as to have lost the 

 chief characters of Composites, the female flowers being naked and not strictly 

 capitate, and the males not having the anthers united.) (Fig. in Eng. & 

 Prantl, iv, 5, p. 222.) 



Species 12, chiefly American. 



