396 PROCEEDINGS OF THE ACADEMY OF [1898. 



RUBIACEiE. 



121. Crusea br achyphy 11a Cham. & Schlecht in Linnaea, V, (1830), L65; Biol. Centr. 



Amer. Bot., II, 57. 



South Mexico, peak of Orizaba at 7,000 feet ; Eslava pedregal, 

 8-10,000 feet, Aug. 31 (399). 



COMPOSITE. 



122. Dahlia Merckii Lehm. Delect. Sem. Hort. Hamb. (1839), ex Linnaja, XIV, 



(1840) 130; Biol. Centr. Amer. Bot., II, 197. 



North Mexico, region of San Luis Potosi, 6,000 to 8,000 feet (Parry 

 & Palmer) ; South Mexico, Real de Monte (Coulter), summit of a 

 mountain near Guadalupe (Bourgeau). This dahlia is one of the 

 showy species ; the color of its flowers runs from purple to pure 

 white through the gradual fading out of the purple color. One 

 most commonly sees in a state of nature the white heads, which are 

 tinted with lavender or pale purple at the base of the ray floret. 

 The heads in each case are nearly uniform in size, being about an 

 inch and three-fourths across. (See an article of mine, " The Na- 

 tive Dahlias of Mexico," Science n. s., VI, 910, Dec. 17, 1897). 



Eslava pedregal, Aug. 31 ; 10,000 feet. 



123. Dahlia coccinea Cav. Ic, III, 33, t. 266. 



Eslava pedregal, 10,000 feet, Aug. 31 ; (see ante). 



124. Dahlia variabilis Desf. Cat. Hort. Par., ed. Ill, 182. 



This dahlia is confined to the region around, including the Val- 

 ley of Mexico. It is a most striking plant, growing from 5 to 6 feet 

 tall, and bearing flowers ranging in color from purple to sulphur- 

 yellow through the following gradations: lavender-purple, helio- 

 trope, heliotrope-yellow (various shades of lighter and lighter hue 

 approaching yellow), sulphur-yellow. The heads in which the ray 

 florets are colored heliotrope-yellow, are in reality of an heliotrope 

 color, the bases of the ligulate corolla being of a yellow color, shad- 

 ing off into heliotrope. They are broad (1 inch), long (2 inches) 

 and ovate spatulate. See " The Native Dahlias of Mexico," (Science 

 n. s., VI, 909, Dec. 17, 1897). 



Eslava pedregal, 10,000 feet, Aug. 31 (390). 



125. Cosmos sp. 



Eslava pedregal, 9,000 feet, Aug. 31 (384). 



126. Stevia nudiflora. 



Eslava pedregal, 9,000 feet, Aug. 31 (385). 



