120 . BOTANICAL GAZETTE [AUGUST 
observed in microspores artificially removed from indehiscent 
anthers. Very feeble germination was also obtained in tests of 
large sized grains from fully dehiscent anthers,-as in no. 2 ee 
many plants completely sterile stamens retain some suggestion 
of filaments and anthers in regard to the general form, but all 
traces of such differentiation may disappear, giving only foliose 
structures as shown in nos. 10, 34, and 35. In general, the 
various grades of development of stamens may well be regarded 
as indicating different grades of maleness. | 
In the case of all plants the flowers of which have here been 
described and illustrated, observations were made of flowers in 
numerous heads throughout at least one season of bloom. Some 
have been under observation for several years. At the extreme 
tip of the spikes in many plants there is a tendency for flowers 
to develop poorly; the pistils usually protrude, but the stamens 
are poorly formed and often flowers fail to open. This is the 
tendency to gynomonoecism especially emphasized by SCHULZ (24) 
and CorRENS (4). This tendency is evidently more marked in 
some plants than in others, but I am unable to make any classi- 
fication on this basis. For the plants already discussed the flow- 
ers were very uniform for at least four-fifths of the spikes, as 
indicated in the spikes (excepting no. 55) shown in pl. 13. 
GRADES OF INTERSEXUALISM 
Variations in the development of stamens in the same flower 
or among sister flowers are frequent for many plants. In such 
cases there are various mixtures of different types of flowers and 
stamens. Some of these may be noted as follows: 
No, 36 (fig. 36).—For this plant some stamens were nearly 
identical with those of the first form, while others were quite as 
in the second form. Differences in the length of stamens in a 
single flower were conspicuous. Some anthers failed completely 
to dehisce, while others dehisced fully. The greater portion of 
the pollen was impotent. Grains of large size were present and 
some of these from dehiscing anthers germinated well in cultures. 
No. 37 (figs. 37, 38, 52).—As in the plant previously noted, : 
there is much variation in the length of filaments among stamens 
