460 VaIL: STUDIES IN THE ASCLEPIADACEAE 
those of A. syriaca in contrast to the long-peduncled terminal 
umbels of A. amplexicaulis. The flowers are intermediate between 
the two species, with the characteristic distinct stripe down the 
back of the hood that appears in fresh specimens of A. amplext- 
caulis. he hoods of A. amplexicaulis vary very greatly in size, 
and in the undulations of their apical margins. 
New York BoranIcaL GARDEN, 
Explanation of plates 16-19 
PLATE 16 
la. Asclepias syriaca L., follicle. 14. Asclepias syriaca L., leaf. 2. Asclepias 
intermedia Wail, leaf. 3. Asclepias amplexicaulis Smith, leaf. 4. Asclepias kansana 
Vail, follicle. 
_Figures 1a, 14 and 3 were drawn from fresh material; 2, from the fresh type 
specimen ; 4, from specimen collected by W. A. Kellerman, 1890, All figures 2% 
nat. size, . 
PLATE 17 
ae syriaca L, 2. Asclepias intermedia Vail. 3. Asclepias amplexi- 
Ga, Smal 
ae 1 and 3 were drawn from fresh material ; 2, from type specimen. 
In each case a, flower, 2. 6, calyx-segments, about 6. c, hood, front 
view, X about 6. 4d, hood, side view, > about 6. ¢, gynostegium, > about 6. f 
pollinia, X 14. 
PLATE 18 
Asclepias kansana Vail. a, flower. 6, calyx-segments. ¢, hood, front view. 
d, hood, side view. ¢, gynostegium, f, pollinia. yg, basal leaf. 4, upper stem leaf. 
The figures were all drawn from no. at collected by J. B. Norton, 1896. 
PLATE Ig 
Asclepias Bicknellii Vail. a, flower. 4, calyx-segments. c, hood, front view. 
d, hood, side view. ¢, stegium. f, pollinia. g, aay leaf. 4A, stem leaf. 
The figures were all drawn ear the type specimen, when fresh. 
