579] ENGELMANN—THE FLOWERING OF AGAVE SHAWII. 
{From the Transactions of the Academy of Sci e of St. Louis , Vo/. III., No. 4.) 
The Flowering of Agave Shawii . 
By Dr. George Engelmann. 
In May, 1876, Mr. Shaw received from San Diego, Cal., 
through the kind offices of Messrs. Hitchcock and Parker, a full- 
grown specimen of the fine species named for him. In June the new, 
innermost, leaves became more slender and their marginal teeth 
smaller. Early in July the flowering stalk began to rise. Regu¬ 
lar measurements of its growth were made by Mr. Gurney, the 
superintending gardener, at 7 o’clock a.m. and at 7 p.m., from 
July 8th to September 5th. I have divided this period of 60 days 
into 6 decades, and have added the mean temperature and the fall 
of rain (at my station, 3 miles northeast of the garden) of each 
decade. The following table exhibits these data : 
AMOUNT OF GROWTH IN TEN DAYS. 
1876. 7F.M.-7A.M. 7A.M.-7P.M. Total. Mean Temp. 
July 8-17. 2| in. 
“ 1S-27. 3 “ 
“ 28-Aug. 6. 4! “ 
Aug. 7-16. 7 “ 
“ 17-26 . 5,“ 
“ 27-Sept. 5. • 4 i “ 3 “ 7l “ 72°-6 
July 8-Sept. 5...27I in. 19^ in. 46I in. 
Rainfall. 
1.26 in. 
1.03 “ 
0.72 “ 
1.51 “ 
2.21 “ 
1.71 “ 
The table shows that the night-growth (including the morning 
hours) was in every decade larger than the day-growth, and in 
the whole period surpassed it by 16 p. ct., the former amounting 
to 58, the latter to 42 p. ct. 
It is further seen that the largest advance was made about the 
middle period, or from the 3rd to the 5th, and mostly in the 4th 
decade. After Sept. 5th the growth diminished rapidly, about 
the end of the month the head began to swell, and 3 months later 
the first blossoms opened. 
The table also proves that the temperature of each decade did 
not have any material effect on the growth of the stalk; in the 
warm weather of the first two decades it grew much less than in 
the cooler 3rd period. 
[Nov., 1S77.] 
Missouri Botanical Garden 
George Engelmann Papers 
