28 MISSOURI BOTANICAL GARDEN. 



World, and Dracaena, Cordyline, Astelia and Milligania, 

 of the Old World, while the South American Heireria is 

 removed to another tribe. 



Professor Engler,* who treats the Aloineae as pertaining 

 to a group placed at a considerable distance from the 

 Dracaeuoideae, includes in the latter the Old World Dra- 

 caeneae, of the genera Cohnia, Cordyline, Astelia, and 

 Milligania, with perianth segments connate at base, and 

 the New World groups Nolineae, of the genera Nolina and 

 Dasylirion, and Yucceae, of Yucca and Hesperaloe, with 

 the segments distinct. f Hesperocallis is very properly 

 removed to another group. 



The present paper deals only with this group Yucceae of 

 Engler, and includes the principal conclusions reached in 

 an intermittent herbarium, garden and field study extend- 

 ing over the last sixteen years, in the course of which nearly 

 all of the spontaneous species have been examined and 

 photographed in their native homes and many of them in- 

 troduced or reintroduced into cultivation in this country 

 and Europe from definitely located sources. 



In its alliance, the group Yucceae is characterized by the 

 possession of similar subequal withering-persistent petaloid 

 perianth segments, a 3-celled ovary with more or less in- 

 truded dorsal false septa, many ovules 2-ranked in each 

 cell, a subterete elongated embryo obliquely placed across 

 the seed, and germination with arched cotyledon.} 



* Natiirl. Pflanzenfamilien. II Teil. 5 Abteil. 19, 70. (1888). 



t It is to be observed that, with most writers, Engler speaks of the 

 segments as free or somewhat united at base, in his generic description 

 of Yucca. 1. c. 70. 



J In all of the genera of this group, in germination the cotyledon as- 

 sumes an arched form, with the seed remnant on or in the soil (from which 

 it is ultimately raised in some cases), instead of directly carrying this 

 up on its end as it commonly does in Liliaceae. See The Garden. 8 : 

 300. /. Gard. Chron. n. s. 24: 216. Lubbock, Contr. Knowl. of Seed- 

 lings. 2 : 578, 613. Copeland, Bot. Gaz. 31 ; 419. /. 3. 



