of the calyx lobes, show no variation. Size in the flowers 
is also constant. 
I have studied five staminate flowers from various 
specimens of the type collection and thirty-six, taken at 
random, from the Fr6ées collections. The number of an- 
thers is extremely constant, being six in all cases but 
two. In these cases seven anthers were found, the unusual 
insertion of an extra anther indicating abnormality. I am 
at a loss to explain Mueller-Argoviensis’ statement that 
the number can vary between six and ten, unless arare 
or abnormal condition existed in the material which he 
studied (necessarily material of the type collection). 
Hemsley (in Hooker’s Icon. PI. 26 (1898) t. 2573, fig. 11) 
indicated six anthers, irregularly inserted in two verticils. 
Spruce, in the original description, described them as 
they are in Hevea guianensis Aubl. var. lutea (Benth.) 
Ducke & Schultes, which has most frequently five, less 
frequently six, but rarely (and probably abnormally) 
seven or eight. It is evident from a study of the new 
collections that the number of stamens is normally and 
quite constantly six. 
No variation of any appreciable degree was noted in 
the size, shape, and insertion of the lobes of the stami- 
nate disk. In all of the flowers examined, they are large, 
very long-acuminate, and conspicuously spreading. It is 
of interest to note that the disk lobes in Hevea rigidifolia 
are larger than in any other species. 
An examination of three pistillate flowers from the 
duplicate type at the Gray Herbarium, two from the type 
at Kew, and fifteen from the several Fr6ées collections has 
served to emphasize the stability of all the important 
characters, with the exception of the indumentum of the 
inner surface of the calyx. The calyx lobes are invariably 
divided about two thirds or three fifths of their length: 
the tomentulose indumentum of the exterior of the calyx 
[ 113 ] 
