SEED PRODUCTION IN YUCCA GLAUCA 
Max M. Et.tis 
In the course of other collecting in the autumn of a ‘au 
data were gathered concerning the amount of seed as nae an 
Yucca glauca. It is well known that this plant depenc s pe a 
Yucca or Pronuba moth (Pronuba yuccasella)' for pollina ag ee 
that the larvae of the Pronuba in turn feed upon some of the ee 
oping seeds of the Yucca. As a result, Yucca produces an re 
of seed. It is concerning this excess of seed and the num be 
seeds eaten that data are submitted. Seed pods of Yucca w 
collected and counts made at Boulder and Wray, Colorado. 
I. Distribution of seed-producing plants 
At Boulder counts were made on three mesas, one north and on 
south of the city, and one near the base of Flagstaff i 
On the south mesa 320 plants were counted and no seed pods ee 
Many of the plants (about half of them) had flower stalks a 
standing. Some of these stalks were discolored and worn, show : 
* them to be more than a year old, but the majority of the pe 
stalks were of this year’s growth. Occasionally a group of a Fe 
plants with old flower stalks, on which were old empty seed pods, 
was found. : d 
On the north mesa 142 plants were counted and none with me 
pods found. Of this number 80 had this year’s flower stalks sti 
standing and 12 had old flower stalks. ; 
Only on the mesa near Flagstaff were seed pods found on = 
year’s stalks. Here 210 plants were counted and ro found wit 
seed pods. These 10 plants were all included within a square of 
200 yards, 
At Wray observa 
side of the Republic 
of the plants seen, 
tions were made on several mesas on the north 
an River. No attempt was made to count all 
but by comparison with the Boulder mesas at 
* Pronuba, although generally used, is preoccupied. The name should stand 
Tegeticula yuccasella, 
ical Gazette, vol. <6] [72 
