402 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



In the present paper twenty-four species and subspecies are included, some of them 

 additions of older species due to more extended exploration of the field, but most of 

 them species described since the appearance of the Biologia Centrali-Americana, or 

 new species first published in this paper. 



The genus is well represented in Mexico, the number of species being only slightly 

 less than that found in the United States. The species are most abundant in the 

 northeastern part of the Republic, especially in the States of Chihuahua, Sonora, and 

 Coahuila. In the extreme southern part and in Central America but two forms are 

 known to occur, the rather cosmopolitan tropical species, AMonia violacea and A. 

 viscosa. None of the species have been reported from the west side of the Sierra Madre. 



KEY TO THE SPECIES. 



Perianth scarlet, with a conspicuous tube, bilobate. (Leaves 



linear) 1- A - coccinea. 



Perianth not scarlet, campanulate, not bilobate. 

 Anthocarp glabrous. 



Leaves linear or linear-lanceolate. 



Stems and leaves glabrous 11. A. glabra recedens. 



Stems densely pilose-viscid above; leaves ciliate 



or pilose-viscid 12. A. gawapoides. 



Leaves not linear nor linear-lanceolate. 



Plants more than 1 meter high, much branched; 

 stems pubescent throughout. 

 Involucres 1-flowered ; stems and leaves vis- 

 cid; uppermost leaves conspicuously 



petioled 2. A. viscosa. 



Involucres 2 or 3-flowered; stems and leaves 

 pnberulent but not viscid; uppermost 



leaves almost sessile 3. A. rotata. 



Plants much lower and less branched; stems 

 glabrous, at least below. 

 Plants very slender, lax (stems often decum- 

 bent); leaves very thin, bright green, 

 net fleshy. 

 Leaf blades ovate, acute; stems without 



gland-tipped hairs 4. A. violacea. 



Leaf blades lance-ovate, obtuse; stems 

 with numerous gland-tipped haira 



above ' 5. A. mollis. 



Plants with Btout, erect stems; leaves usually 

 thick and fleshy, often glaucous. 

 Involucres usually 3-flowered. 



Leaf blades 40 to 70 mm. long, cor- 

 date; inflorescence naked, 



corymbose 6. A. cardiophylla. 



Leaf blades 35 mm. long or less, 

 truncate at the base; inflo- 

 rescence leafy, irregularly 



panicled 7. A. del to idea. 



Involucres 1-flowered. 



Inflorescence paniculate 8. A. texensis. 



Inflorescence corymbose. 



Leaf blades narrowly lanceo- 

 late, 3 times as long as 

 broad; involucres 4 mm. 

 high or less 9. A. microchlamydea. 



