32 TRANS. ST. LOUIS ACAD. SCIENCE. 



be one of the most variable species, perhaps, only because we 

 know more of it than of the others. 



SEEDS. 



The seeds of the Yuccas are compressed, of a triangular-obvate 

 or obliquely ovate, or sometimes even orbicular form, the straight- 

 er, inner margin with the indistinct raphe corresponding with the 

 secondary dissepiment, and the angle at its base containing the 

 hilum. They vary in size from 6-12 or 13 raillim. in diameter, and 

 0.6-3.5 millim. in thickness. The thin black more or less opaque 

 testa exhibits, under a strong power, elevated cells or tubercles, 

 each with or without one or several pits or impressions ; in some 

 forms these cells appear larger and irregularly rugose, but I have, 

 thus far, not been able to discover constant specific characters even 

 in the seed surface. 



The seeds are of three different forms, corresponding with the 

 three kinds of fruit. The baccate Yuccas have the thickest seeds 

 (2.5-3.5 rnm.), of an uneven rugose or undulating surface, with 

 a very narrow two-edged rim, and a deeply lobed or ruminated 

 albumen, as already indicated by Torrey, in Bot. Mex. Bound., 

 in the instance of K baccata ; I have been able to examine only 

 the seeds of this species, T. aloifolia and T. Treculiana. Clisto- 

 yucca has a thinner seed (2 mm.), with a little more distinct rim| 

 and with an even albumen. All the capsular Yuccas have the 

 thinnest seeds, (0.6-1.2 mm.) with a very distinct, narrower or 

 wider, thin and brittle margin, and with an even albumen. 



The semi-transparent, hard, almost corneous, farinaceous and 

 oily albumen, ruminated in Sarcoyucca^ plain in all the others, 

 contains the straight or mostly more or less curved axil embryo 

 which extends diagonally from the hilum, to which the short 

 caulicle points, almost to the opposite margin, thus attaining the 

 full length of the albumen. Only very rarely and in imperfect 

 seeds I have seen a shorter embryo, such as Gaertner figured, and 

 Kunth described, as being less than one-half or only one-fourth 

 as long as the diameter of the albumen. The slit in the base of 

 the cotyledon, under which the plumule is concealed, shows the 

 cotyledon to be about four or five times as long as the caulicle. 



MONSTROSITIES. 



I have seen very few abnormal developments of Yuccas, and 

 these only in the flowers. Tetramerous flowers with an eight- 



