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MAY 12 1898 
NACHWIRA ER ws C HENGE 
A Monthly Review of Scientific Progress. 
No; 15;. Vor jl. MAY; 1893: 

NOTES AND COMMENTS. 
THE PoLLINATION OF THE YUCCA. 
\q Rk. A. W. BENNETT, in his article in the March number of 
i NaTuRAL SCIENCE, refers to the pollination of the Yucca, a well- 
known liliaceous plant, by a moth (Pronuba yuccasella), and those in- 
terested in the subjéct will find some ‘‘ Further Studies,” by William 
Trelease in the fourth annual report of the Missouri Botanical Garden. 
Hitherto, only two species, filamentosa and glauca, have been directly 
observed under cultivation, and the latter wild in Colorado, and the 
moth Pyonuba is the pollinating agent in both. The present report 
describes further investigations in the field on these and other species. 
The flowers of Yucca baccata, a widely distributed species, ranging 
in a variety of forms from southern Colorado into Mexico and Cali- 
fornia, are frequented by a moth somewhat larger and a little darker 
in colour than the P. yuccasella of the Mississippi Valley and Rocky 
Mountains, but otherwise indistinguishable from it, as is also the 
moth of the Gulf region. Like the Eastern representative, it rests 
within the flower during the day with the head directed towards 
the base of the stamens, and when depositing the egg, at night, 
‘* doubtless backs down between the upper ends of the stamens,” piercing 
the ovary at about its middle in the thinnest part, viz., that between 
the internal partitions, which is not covered by the lower part of the 
stamen. ‘‘ After thus depositing the egg in the ovule of the plant, the 
females behave as in Y. filamentosa, carrying loads of pollen from the 
anthers and thrusting it into the cavity of the stigma with the 
proboscis. This open canal is frequented by numbers of a white 
Thrips, which sometimes penetrate the cells of the ovary and doubt- 
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