ENGELMANN — NOTES ON THE GENUS YUCCA. 33 



parted perigon, eight stamens and a four-carpellary ovary and 

 fruit, more or less regularly developed, are not quite rare in cul- 

 tivated as well as wild plants. In overgrown garden specimens 

 of T. angustifolia, I have seen flowers irregularly doubled, the 

 number of perigonal lobes increased, some of them yet bearing 

 the traces of anthers, or filaments bearing perfect anthers, with 

 petaloid excrescences or wings, also filaments adnate to the ovary, 

 and some of them even tipped with the green stigma of the species. 

 In a cultivated form of T. jilamentosa, the floral axis was elon- 

 gated, the perigonal segments separated and increased in num- 

 ber, the exterior somewhat foliaceous, and bearing regular or ir- 

 regular axillary flowers. 



GEOGRAPHICAL DISTRIBUTION. 



Yucca is a peculiarly American genus, the limits of which were 

 said by the old botanists, Linnaeus 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 coun- 

 tries 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 35th deg. N. lat. On 

 the eastern coast, one species, T. flamentosa, 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, T. angustifolia, reaches as high up 

 as 44 or 45 . Southward, a form allied to Y. aloifolia has cer- 

 tainly been met with in Yucatan ; and another species, T. Gua- 

 temalensis, 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 T. 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 ( T. angustifolia and T. rupi- 

 cola) extend beyond the Rio Grande into Northern Mexico. The 

 baccate Yuccas are the more southern, caulescent, forms, and 

 some of the species do not come up into our territory. The east- 

 ern and western species are entirely limited by the Mississippi, 

 which none of them seem to cross. T. angustifolia is a native 

 of the great plains from north to south, and also extends south" 



iii — 3 t Ma y '- iS -3-i 



