28 BULLETIN 75, U. S. DEPARTMENT OF AGRICULTURE. 
TaBLe XIX.— Weight (in grams) necessary to trip alfalfa flowers on different plants at 
different stages of maturity. 
AT ALMA, NEBR.1 













Young Prime Old 
Plant. flowers. | flowers. | flowers. 
SOY OM (2 A gt A ae ety Pa as he Aa ES Ee en Ne las EW unl yas Hoya 2.14 1. 49 0. 68 
eat gt a Te 38 oS en hy em ee ce a ae A Coen Ooh epeer er Minn oe cae Sr shel Ce 3.89 So Asay / 
LN Deca) G74 Wi Tas APR ah iy SN pat Pes A Se eae RO he. Shs LI gs a LN ca ar tlk 6. 42 3. 56 2. 60 
MD So Sec Rs ee Se AS ec! See ge IIe an, bp eRe aay 2. 54 1.30 
a Dee ak ae Sa cert ete oe Re ee AE eke NPR pO cee Sie epee OMe eee a fsa 3. 69 2.14 
Average ts. O14. Meare foes eth SRE teed epee oe | 5.18 2.92 2.07 
AT ARLINGTON FARM, VIRGINIA.2 
UAC MT AGO RES Soy sem cts ses Be Re es ERD Se ee ee ae We ee 6. 57 ate, 1.68 
ve ota eal Buk: D7 (Ae ates a eee EE en Ae UR Ae RR ees ee ee Eee are 2. 07 1.49 335: 
Sh fice lav DAP Me AE LE oll sat tle ple ane ai al ated Seam P ded a se 4 4.79 3. 04 | 45 
SSS i 
yA oes ele ae ce Oe a ap Oe Nite Sol Oe, 2 | 4,94 | 2.33 | 71 
1 Experiment performed August 4, 1908. ‘Temperature 98° to 101° F.; humidity very low; bright sun. 
Number of flowers used in experiment as follows: Young, 16; prime, 22; old, 21. 
2 Experiment performed July 2, 1908; used one flower at each stage of maturity. 
Observations made at different times and places indicate that 
wind or rain do not ordinarily cause alfalfa flowers to become tripped. 
Even when blowing with high velocity the wind sways the plants 
back and forth usually without causing the racemes to strike against 
adjoining plants. At Chinook, Mont., during a high gale accom- 
panied by a rainstorm, which lasted for a few minutes, a small pro- 
portion of a number of flowers that had been marked was tripped. 
The number of flowers which become tripped through the influence 
of wind or rain, however, in ordinary seasons is evidently small. 
EFFECT OF PARTIAL SHADE. 
In conducting the experiments described in this paper it has been 
observed that on the different plants used those flowers which have 
been inclosed in the covering made by a single thickness of mosquito 
bar remain in bloom longer and that the petals seem to be larger 
than on those flowers which were not inclosed. As it seemed possible 
that the effect of the slight shade or the breaking of the force of the 
wind might also influence the development of pods and'seed, an experi- 
ment was performed at Pullman, Wash., in 1908, to obtain some infor- 
mation in regard to this point. 
Several plants were selected, and a portion of each plant was 
inclosed in a tent made of netting (tarlatan); the remaining portion 
of each plant was not inclosed, but was protected on three sides and 
partially from above by one thickness of netting, which was between 
the plant and the sun and also between the plant and the prevailing 
winds, yet did not prevent the access of bees and other insects. 
The results of this experiment are shown in Table XX, in which the 
results secured on unprotected plants at the same time and place are 
also presented for the purpose of comparison. 
