ENGELMANN NOTES ON THE GENUS YUCCA. 2j 



obscurely six-sided ovary, sometimes irregularly impressed and 

 angled by the close application of the stamens in the bud, rarely 

 attenuated at base ; terminated by three, more or less united, stig- 

 mas, which are usually sessile, or are elevated on a style formed 

 by the gradually attenuated upper part of the ovary. Only in T"* 

 Guatemalensis the ovary is more oblong than prismatic. 



The ovary consists of three carpels, opposed to the exterior 

 perigonial lobes, forming by their connection three primary dis- 

 sepiments each one bearing on two central placentas two series 

 of numerous flat, horizontal anatropous ovules on very short (not 

 long, as is sometimes stated) funiculi, separated from one an- 

 other by a secondary dissepiment, springing from the back of the 

 carpel ; the single ovules, however, are not separated by trans- 

 verse dissepiments as Gaertner has it 



The Yuccas with thick seeds and fleshy fruit bear thicker 

 ovules (0.3-0.4 and even 0.5 millim. thick), those with thin seeds 

 and capsular fruit thinner ones (0.2-0.25 mm. thick), so that to 

 some extent we may, from the thickness of the ovules in well 

 developed flowers, guess at the section to which the plant may 

 belong. T. gloriosa and 2". Treculiana, however, have some- 

 what thinner ovules than the others of their section, and in some 

 forms, which I class with Y.jila?nentosa, I have found them oc- 

 casionally as thick as these. 



The three carpels are firmly united from the centre of the ovary 

 to beyond the middle ; here a thin tube, open at the base and top 

 of the ovary, and from this to the external surface a more or less 

 closely compressed slit, separate them. These slits open as the 

 fertilized ovary grows, and in the fleshy-fruited species eventually 

 form the three inner, impressed sides of the six-sided pod. 



The always glabrous ovary is either obtuse and abruptly termi- 

 nated by the stigma (T. aloifolid), or it is gradually attenuated 

 into a conical or prismatic, glabrous style, sometimes as long 

 as the ovary itself ( T. rupicola), which towards the tip ends in 

 the stigmas. This style is an organ of great variability in length 

 and thickness, and may or may not be present in forms of the 

 same species. 



Stigmas we conventionally call the terminations of the three 

 carpels, which are distinguished from the ovary and style by their 

 coating of transparent oval or globose epidermidal cells, which, 

 however, as already stated, have no stigmatic function, not even 



