Feb. a, 1924 
The Blooming of Wheat Flowers 
233 
Immediately after recording the time of blooming of a flower, the 
empty extruded anthers were removed with forceps in order to facilitate 
observations and to prevent confusion in recording the data. Great 
care was required in this procedure since the slightest jarring or touching 
of a head while blooming is likely to hasten the opening of the flowers. 
A flower was considered as having bloomed as soon as noticeable separa¬ 
tion of the lemma from the palea occurred. 
THE BLOOMING PROCESS 
Under favorable conditions the wheat flower blooms by opening its 
glumes, slowly at first, then more rapidly, until the tips of the lemma 
and palea are separated, usually 3 or 4 mm. After the glumes open 
the anthers are pushed upward by the elongating filament and when 
fully extruded assume a pendent position. At some time during these 
processes the anthers dehisce apically along the lines joining the cylinders 
into pairs. This splitting may take place in one or more anthers by 
the time they are first clearly visible, while in others it may be delayed 
until the time of full extrusion. A number of flowers were observed 
whose anthers were completely extruded and pendent before dehiscence 
occurred. Some flowers were found which had retained within their 
glumes one, two, or three anthers, quite often lodged in the folds of the 
palea. Other flowers were found with anthers partially protruded and 
imprisoned between the tips of the glumes. The greatest length of 
filament observed was 10 mm., exclusive of the anther, which was 3 
mm. long. In one instance a filament was observed to attain its full 
length of 10 mm. in 10 minutes. Askenasy (j) 2 measured a number of 
filaments of wheat and rye flowers. He states that in most cases the 
filaments have grown from 1 to 1 % mm. per minute. 
Very soon after full extrusion, and assisted by the inversion of the 
anthers, the pollen is fully emptied from the anther sacs. Some of it, 
probably at least one-third, usually falls within its own flower, resulting 
in plentiful pollination of the stigma. The remaining pollen is scattered 
about and may fall upon the stigmas of other flowers. Cross pollination 
apparently is sometimes effected in this way, especially when the anthers 
of neighboring flowers have been removed, as shown by Leighty and 
Hutcheson (£), or have aborted. 
When conditions are unfavorable for the opening of the glumes, the 
anthers of the wheat flower shed their pollen and effect fertilization 
without being extruded, or they may be extruded only at the tips.* 
Nearly 5 per cent of the flowers, or 19 out of a total of 406, under obser¬ 
vation in this study, behaved this way. Each of the heads under 
observation had one or more such cleistogamous flowers, the maximum 
number on any head being six. Kernels were procured from all of 
these flowers. Under certain environmental conditions wheat flowers 
may be quite generally cleistogamous. 
TIME REQUIRED 
The process of blooming of wheat flowers is variable. Some flowers, 
have been observed to open in less than 1 minute. Others require 
3 minutes or more. Observations on the time elapsing between the 
beginning of opening and the time at which the anthers attain the 
* Reference is made by number (italic) to “ Literature cited,” p. 244. 
