NOTES ON THE GENUS YUCCA, 287 
GEOGRAPHICAL DISTRIBUTION. 
Yucca is a peculiarly American genus, the limits of which were said by the old botanists, 
Linneus among them, to extend from Canada to Peru. It is certain, however, that no Yucca grows 
in Canada, and I find no evidence of any being indigenous in countries south of the Equator. The 
greatest development of the genus is found in Northern Mexico, and the Southern United States, to 
the Pacific, principally between the 25th and 38th deg. N. lat. On the eastern coast, one species, 
Y. filamentosa, extends as far north as 38°, while on the western so much milder slope, they are not 
found farther than 35°, or perhaps 36°. On the western plains, the hardiest species, Y. angustifolia, 
reaches as high up as 44° or 45°. Southward, a form allied to Y. aloifolia has certainly been met 
with in Yucatan ; and another species, Y. Gwatemalensis, is said to be a native of Central America. 
I have seen no specimens from the West Indies, though many authorities credit these islands with 
Y. aloifolia, nor have I seen any from South America. 
The capsular Yuccas represent the low or herbaceous northern type of the genus; all the 
known species belong to the United States, and only two of them (Y¥. angustifolia and Y. ruypicola) 
extend beyond the Rio Grande into Northern Mexico. The baccate Yuecas are the more southern, 
caulescent forms, and some of the species do not come up into our territory. The eastern and 
western species are entirely limited by the Mississippi, which none of them seem to cross. Y. 
angustifolia is a native of the great plains from north to south, and also extends south- 
westwardly into the mountain region; Y. rupieola inhabits the southern portion of the [34] 
plains. Clistoyueca and Hesperoyucca are southwestern types, peculiar to Arizona an 
California. 
SYSTEMATIC ARRANGEMENT. 
In the foregoing pages it has been shown that in the fruit and seed we have excellent char- 
acters for the arrangement of the species of Yucca into several very natural groups; the nature of 
the edge of the leaves furnishes proper subdivisions; the specific characters are based upon the 
differences of trunk, leaves, flowers, and also of fruit and seed. 
YUCCA, Livy. 
Perigonium patulum demum_ globoso-campanulatum 6-partitum dstaaiene ms; segmenta lanceolato-ovata 
acutiuscula; filamenta clavata multo breviora; anthere biloculares introrsum dechiinsisten parve; pollen globosum ; 
ovarium tricarpellare triloculare, loculi incomplete bilocellati: stigmata 3 e inata plus minus connata tubum stig- 
maticum efformantia; ovula plurima compressa horizontalia anatropa brevissime funiculata 6-seriata; fructus baccatus 
seu capsularis incomplete 6-locularis; semina obovato-triangularia compressa horizontalia 6-seriata nigra, embryo 
diagonalis albumini corneo equilongus 
Plante in America tropica cis wequatorem et preecipue in boreali calidiore indigene; candice arborescente elatiore 
vel humiliore, seepe hypogeo ; foliis in apice caudicis confertis lineari-lanceolatis crassis rigidis rarius flaccidis apice 
plerumque spinescentibus; panicula terminali multiflora subsessili vel in scapo bracteato ‘elata; floribus majoribus 
albidis pendulis nocturnis. 
I. Evyucca: serch el avata obtusa papillos apistillo pleramque breviora demum patula vel recurva ; anthere 
cordato-sagittate ; um prismaticum ; stigmata papillosa. 
A. Sacer poe jndehiscens baccatus pendnlus; semina crassa undulata immarginata albumine 
lobato-ruminato, Plante plerumque arborescentes, panicula sepius sessili. 
* Folia margine serrulato-asperata. 
1, Yucca ALOIFOLIA, Linn.: caule elatiore ; foliis lineari-lanceolatis supra leviter concavis nunc rigidis pungen- 
tibus levibus margine asperrimis; bracteis panicule subsessilis ovate vel oblonge glaberrime aeinontbes | trian- 
gularibus marcescentibus; perigonii segmentis ovatis ; staminibus ovarium prismaticum oe sessilibus [35] 
brevibus crassis rectis coronatum nunc aquantibus demum patulis; bacca prismatica 6-angulari acutiuscula. 
