FLOWER OF ADENOCAULON BICOLOR 
JEssIeE A. AYRES 
(WITH PLATES XI AND XII) 
Adenocaulon bicolor Hook. is distributed from the Himalaya 
Mountains to Japan, and from the northwestern part of the 
United States to Lake Superior. The only other species is A. 
chilenae Less., from Chile to the Straits of Magellan. The plant 
is a peculiar one, having no pappus, but an abundance of glandular 
hairs on the seed. This work was undertaken under the direction 
of Dr. T. C. FRvE of the University of Washington, with the object 
of comparing the development of the staminate and pistillate 
flowers. 
The heads are arranged in a raceme (fig. 1), which appears as 
a swelling between the upper leaves (fig. 2, s). On this swelling 
cycles of protuberances appear (fig. 3, a, c), which become the 
bracts of the inflorescence subtending the peduncles; but the 
uppermost whorl becomes the involucre of the terminal head 
(¢ in figs. 4-9). When the involucre arches over the head, the 
primordia of the individual flowers appear as bulges on the recep- 
tacle (figs. 6 and 7,7", 7). Some of the primordia divide, thus 
increasing the number of flowers (figs. 8-10, «). This mode of in- 
creasing the number of flowers suggests a tendency in the heads to 
branch, and points toward a probable ancestral form with scattered 
flowers. The axillary heads appear shortly after their bracts arise 
(fig. 9, 6). The flowers develop in acropetal succession, as do the 
parts of the individual flowers (fig. 10). 
In the staminate flowers, when the floral parts begin to develop, 
the flower primordia first broaden at the top (fig. 9, p). The 
corolla then appears as a marginal ring (fig. 10, mr) on the top. 
After the corolla tube lengthens and begins to curve inward, a 
ring of small bulges appears in the throat of the tube; these are 
the beginnings of the stamens (fig. 10, st). When the stamens are 
well started, the carpels appear beneath them (fig. 11, ”, ca). 
us all the normal parts except the calyx are present (fig. 12, ” ): 
When the bundle enters the staminate flower, it separates into 4 
Botanical Gazette, vol. 59] (154 
