J01MAL OF AOtlQILT IML KESEARCH 
Vol. XXVII Washington, D. C., Feb. 2, 1924 No. 5 
THE BLOOMING OF WHEAT FLOWERS 1 
By C ' E fi~ H 7pf d , SA r, D °.’ Agronomists, Office oj Cereal Investigation, 
Bureau of Plant Industry, United States Department of Agriculture 9 
INTRODUCTION 
• J- me 7 d rnaniler °f blooming of wheat flowers is the result of the 
mteraetion of mternal and external factors. When flowers have reached 
the blooming stage, the exact time and rate of blooming is determined 
to a large extent by meteorological conditions. 
The observations on wheat flowers reported in this paper were made 
P£ m . an J y f . or the purpose of procuring additional information on the 
effect of external factors on blooming. 
METHODS AND MATERIALS 
The plants on which most of the observations were made were volun- 
teers growing m a garden in Washington, D. C. They were of the Fultz 
type (Trthcum vulgare), having the following characters: Plant winter 
habit; spike, awnless; glumes, glabrous, white; kernels, red, soft. More 
lho»t 4 u?« fl ° Wer 7 m SCVen he ? ds 0I 7 0ur P lants - which began to bloom at 
about the same time, were chosen for observation. Additional observa¬ 
tions were made on plants growing in the field and in the greenhouse at 
Arlington Experiment Farm, Rosslyn, Va. g enno at 
A plane view diagram of a wheat head illustrated by figure i shows 
the method used for recording the data. In figure i the rectangular 
spaces inclosed by solid lines represent the odd-numbered spikelets 
5“ nd T ° n 1 Slde ° f a . head - numbering from the base of the head, and 
s , pace f lncI °sed by dotted lines represent the even num¬ 
bered spikelets found on the opposite side. The spikelet number is 
W T? m he K arge Square located in the “iddle of each rectangular 
fnHL-at n , ambe f in t h . e smaI1 squares adjoining the large square 
indicate the alternate position of each flower on the spikelet from the 
owest to the highest. The exact time of blooming wasrecorded S he 
spaces opposite the flower number. 
Flowers blooming cleistogamously were recorded as “dehisced inside ’’ 
Blank s pa ces indicate sterile flowers. On spikelets 6, 7, 12, and 12 of 
the data 4A ^ fig ' *’ fifth flowers bloomed but were not included in 
The seven heads chosen were watched continuously for six days, with 
the exception of a short period each night between 10 p. m. and 1 ss 
bi' en . 1 . ltt , 1 , e ac . t ,7 e bloomin g occurred, and the exact time of bloom¬ 
ing of practically all flowers was recorded. Observations at night were 
made with the aid of a small electric flash light which was directed on 
iXmSlorreS n ^ en ° Ugh ° Dly * pr ° CUre the necessar y 
1 Received for publication, Dec. 13, 1923. 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXVII, No. 5 
Feb. 2, 1924 
Key No. G~36r 
74024—24 -1 
(231) 
