AGAVE IN THE WEST INDIES—TRELEASE. i) 
Leaves broad or curved, fleshy. (Native.) 
Plants moderately large, suckering, bulbiferous. Leaves green, transiently glaucous; spine acicular, involutely 
erooved; prickles rather close together. Flowers and seeds medium-sized. (VIVIPARAE)....- Agave vivipara. 
Plants large, not suckering, bulbiferous. Flowers and seeds rather large. 
Spine obliquely mucronate from an involutely slit tumid base; prickles rather close together. Leaves green. 
(CARIB ATAE) Sseeae Soe ea as cr ya ea ISE SIS cialalare ayelelelcieie s)e,cisicimsaiciclavela(ale vautasegeas A. Karatto. 
Spine conical; prickles rather distant. 
berestecen, (UNNm WON) son ceenecaoeuec t EF eae aodbcs 5b6 so eoe Cosa TaeossoSsEnseeaaar A. antillarum. 
ILGRMES ERR, ((BVNTARININE)\ = ooo beseteo sp oocne gece escdcec cu de doceecpmpeasecduceépeagse A. bahamana. 
Plants moderately large, not suckering or bulbiferous. Leaves green or slightly glaucous; spine conical, narrowly 
grooved; pricklesrather distant; flowersand seedssmall. (ANTILLARES)..............--.-.--- A. Willdingii. 
Leaves narrow, erect, firm. (Native.) 
Plants small, suckering, not bulbiferous. Leavesfew, gray; spine conical; pricklesrather close together. Flowers 
SO MEPEeCGsinmall gs (INA GUISNGES) pe <2 .ete(eeie slarsinis sone oie eee naively le Sie) = o1s.o nya sinPne aa esse A. Nashii. 
Leaves narrow, spreading, firm. (Introduced.) 
Plants moderately large, suckering, bulbiferous. Leaves numerous, grayish; spine conical; prickles rather 
distant. lowers andseeds large. | (SISATANAE) ®: 05.) 2.2 isan cose lee cece seceec sees A. angustifolia. 
Inferences from examination of the plants and from analysis of their geographic distri- 
bution are: (a) That even narrow sea channels here constitute all but insuperable natural 
barriers to their dissemination, notwithstanding that the century plant is known to be cast 
up occasionally along the Mediterranean in viable condition; (b) that the significance of a 
channel barrier lies rather in depth of submergence, corresponding to lapse of time, than in 
width; (c) that the narrow but very deep channel separating the Greater Antilles from the 
Caribbean chain has afforded a longer isolation than the chasm between Jamaica and Haiti 
or the channels that part the Caribbees; and (d) that the Bahamas have had more recent 
interchange with the Greater Antilles than has existed between these and the Caribbees, though 
less recent than that between adjacent islands of each group. 
The closer relationship between the large-flowered insular groups of species than with any 
focal group of the mainland suggests that they have been derived through one rather than 
more than one continental immigration, and that they have been isolated from the ancestral 
source for a period longer than that of their separation from one another. The small-flowered 
Antillares may have originated locally in the mountains of Cuba from the large-flowered Antil- 
lanae; whether they furnished the parent stock of the Inaguenses, modified under unusually 
arid conditions, is a matter for less founded conjecture; but this latter group can hardly be 
accounted for otherwise, except by the assumption of an additional immigration from the 
mainland of an ancestral form which left no recognizable traces in the islands over which it 
must have passed. 
There can scarcely be a doubt that the parent stock of the West Indian agaves, which are 
all paniculate, was derived from North America rather than from South America. Apart 
from the Viviparae common to the Leeward Islands and the coast region of Venezuela, the 
genus is not known as native to the southern continent except for one minute form (Agave 
pumila) reputed to occur in the Andes of Colombia, belonging to the spicate subgenus Littaea, 
and four as yet unnamed very glaucous small-prickled forms noted by Werckle! as occurring 
toward the headwaters of the Magdalena River of Colombia, which may be allied to A. Wercklei. 
North of the Isthmus, Agave is represented by many greatly diversified species of both Littaca 
and the paniculate subgenus Huagave. 
It is hard to resist a belief (a) that perhaps, though not probably, with exception of the 
Viviparae, the genus penetrated from Yucatan to and through what are now the West Indies 
at a time when they formed a continuation of the Central American mainland; (b) that the 
Bahamian group derived its stock through later and transient union with the Greater Antilles; 
(c) that the Caribbean volcanic peaks were united by land at one time during the insular history 
of the genus, though they are now divided by deep-sea channels; and (d) that the peculiar species 

1 Monatsschr. f. Kakteenkunde, vol. 17, 1907, p. 122. 
