301 



leaves near the ground and reaches sometimes a height of twelve feet 

 or more, and I present herewith a photograph which very well illus- 

 trates the magniticence of some of the larger specimens (Fig. 38). At 

 my request Mr. I). W. Coqnillett, of Los Angeles, Cal., made some spe- 

 cial observations last year on the pollination of this species, and on the 

 12th of June he was able to witness the operations both of ovipositiou 

 and pollination on a i^lant while yet the sun was shining brightly 

 about forty minutes before setting. The act of ovipositiou does not 

 differ in any particular from that which I have already described in 

 detail for Pronuha yuccasella. The pollen is deliberately gathered 

 and a mass nearly half the size of her head is held under the neck by 

 the coiled tentacles. In pollinating, the tentacles are uncoiled and 

 stretched so that the tips may be inserted into the upper part of the 

 stigma. Mr. Coquillett describes the process of thus pollinating the 

 stigma as lasting about half a minute, after which the insect that he 

 watched descended the ovary and at once mounted to the top of one 

 of the stamens. Here, with her tentacles, she removed both pollen 

 masses (moving her head from side to side during the operation) and 

 added the pollen thus gathered to the mass which she was already car- 

 rying. She went to two other stamens in succession, gathering a pol- 

 len mass from each. Mr. Coquillett in communicating his observations 

 renuirks that " it was indeed surprising to witness the evident intelli- 

 gence which this insect displayed in all her actions wherever the pistil 

 of the flower became pollinated solely through her own labors, and 

 that she went through these maneuvers with the evident intention of 

 pollinating the flower appears to admit of no doubt." 



A number of insects have been observed associated with the flowers 

 of Yucca ?(7/ti/?j9?^i, but none of them, as observed by Mr. Coquillett, acted 

 in any way to produce pollination, either intentionally or by accident. 

 As a check to prove the influence of Pronuba on the production of fruit, 

 1 desired Mr. Coquillett to inclose another panicle and exclude the moths. 

 We were both somewhat surprised at the result, namely, that a certain 

 number of the pods set on this panicle; and this would prove that (so 

 far as a single experiment justifies conclusion) the species is capable of 

 a certain amount of self-fertilization. 



So far as they go, Mr. Coquillett's observations on the actions of 

 Pronuha maculata agree very well with those of Prof William Trelease, 

 who made a special trip through the Southwest, in the spring of 

 1892, with a view of studying the pollination of those Yuccas which had 

 not hitherto been studied in this connection. He has published a most 

 Interesting article in the Fourth Annual Keport of the Missouri Botan- 

 ical Garden, entitled '' Further Studies of Yuccas and their Pollina- 

 tion." This is, in fact, a most valuable contribution to our knowledge 

 of the subject, and is complementary and additional to my own paper 

 published in the annual report of the same series for the previous year. 

 23123— No. 5 2 



