82 MISSOURI BOTANICAL GARDEN. 



recurvifolia and Y.flexilis are, suggests the possibility that 

 the connecting varieties may really be of hybrid origin. 

 Opposed to this supposition, however, are the absence of 

 any recorded history of their source or origin ; the fact 

 that they have appeared in cultivation and are classed with 

 plants likewise of garden origin or long cultivated and in 

 their other forms giving evidence of considerable variabil- 

 ity ; and, particularly, the facts that, except for Y. aloifolia, 

 the Yuccas spontaneously fruit with extreme rarity away 

 from their native home unless, as seems not to be the case 

 in European gardens where these forms have made their 

 appearance, a moth (Pronuba yuccasella} upon which their 

 pollination almost absolutely depends has been introduced 

 with them, and that most persons who have tried to fertil- 

 ize the plants of this genus have met with little or no sus- 

 cess. Still, suggestion of such hybrid origin has been 

 made,* and the most positive proof is at hand that along 

 the Mediterranean coast, at least, skilful operators can not 

 only intercross these so-called species but can also hybrid- 

 ize them reciprocally with other very distinct species both 

 of the baccate and capsular sections of the genus. Thus, 

 for instance, M. Deleuil, of Marseilles, in and subsequent 

 to 1874, crossed Y. aloifolia variegata and Y. alba-spica 

 (whatever that may be), Y. aloifolia variegata 5 with Y. 

 pendula (or recurvifolia}, Y. plicata (or gloriosa plicata} $ 

 with Y. angustifolia vera (or glauca}, Y. plicata with Y. 

 X laevigata { = aloifolia variegata X alba-spica}, Y. pli- 

 catayvfitkY.jilamentosa, Y. plicata $ with Y. Treculeana, 

 Y. cornuta (or Treculeana} <j> with various species, Y. 

 aloifolia variegata with Y. angustifolia vera, Y. gloriosa 

 longifolia (or Y. flexilis glaucescens ?) $ with various spe- 

 cies, Y. X laevigata % with Y. filamentosa, Y. cornuta and 



* Ellacombe, for instance, supposed the T. Ellacombei of gardens, 

 which I take to be synonymous with Y. gloriosa nobilis, to be a probable 

 cross between Y. recurvifolia and the garden form known as T. gloriosa 

 euperba. Garden. 16: 257. 



