302 



Mr. Trelease's life- studies of Y. tcMpplei have added materially to, our 

 understanding of its floral cliaracteristics. Tlie anther cells, on dehisc- 

 ing, contract so as to expose the pollen freely, but the contents of each 

 cell forms a '' rather consistent, two-lobed moist mass, which is held by 

 its lower part, but protrudes prominently from the open anther." The 

 ovary is free from the longitudinal depressions which in the other Yuc- 

 cas usually correspond with the appressed stamens. The capitate 

 stigma is slightly indented at the center ^' and covered Avith long, hya- 

 line, delicate papilla, which are always moist with abundant secretion, 

 that at length becomes almost gelatinous over the middle of the stigma." 

 He found the nectar apparatus well developed, the septal glands though 

 narrow reaching commonly to the base of the ovary, with a conducting 

 groove of corresponding size. The glands are also, though smaller, 

 more active than in most other species of Yucca studied by him. Prof. 

 Trelease also notes that the characteristics of this flower would seem to 

 make it easily self fertilizable, and remarks on the exceptional occur- 

 rence in the lower part of the Cajon Pass of a few plants with more or 

 less abundant, partly developed, but unusually diminutive cajjsules, in 

 which no evidences of Pronuba action were to be found, and this, added 

 to the experiment made by Mr. Coquillett, would seem to indicate 

 that where Pronuba is absent tvMpplei has the same exceptionally lim- 

 ited power of fructification, whether by self-pollination or pollination by 

 other agents, that we know to be possessed by aloifolia among the 

 true Yuccas. Eecognizing this possibility. Prof, 'i'release was some- 

 what surprised to find that, with the single excex)tion which he noted, 

 no fruit, among all his observations, was discovered which did not 

 clearly show the work of Pronuba. 



From his account, as well as that of Mr. Coquillett, it appears evi- 

 dent that Fronuba maculata, in accordance with the greater tendency 

 of the flowers of icMpplei to open during the day, is more diurnal in 

 habit than Pronuba ynccasella, carrying on the acts of oviposition and 

 pollination during the day. Further, unlike the other Pronubas so far 

 known, this species rests with the head toward the stigma, and when 

 disturbed is very apt to drop suddenly from the flower and take wing. 

 I can not do better than quote verbatim Mr. Trelease's interesting 

 account of the act of pollination, that of oviposition being, as already 

 stated, absolutel}^ the same as in yuccasella. 



When the motli is about to deposit an egg she usually moves about in the lower 

 part of the flo^yer much as the other species do, commonly dragging the tip of the 

 ovipositor along the parts she Avalks on as if wiping off extruded secretion, but also 

 seemingly using it as S, tactile organ while she assumes the position best suited to 

 oviposition, which is nearly the same as that taken while at rest. Standing on the I 

 side of the pistil, she then bends the abdomen sharply forward so as to bring the 

 ovipositor to about the middle of the ovary, which she pierces at the thinnest part, 

 namely, about 1™"^ from the septal groove. As a general thing not more than six 

 eggs are laid in a given pistil — one on either side of each septum — and frequently 

 the number is smaller than this, so that even if they all hatch, which is not likely 

 to be the case, there is rarely more than one larva to each tier of seeds, and con- 



