152 



of these species, however, have not been unobserved. 1 Some Manfredas 

 (at least one) have been described as Polianthes, and two Agaves 

 (§ Manfreda) have been called A. polianthoides. Baker has also called 

 attention to their close relationship with Polianthes and Bravoa. I 

 find that, except in the flowers, these herbaceous Agaves have all their 

 relationships with Polianthes and its allies, which they resemble, 

 namely, in their herbaceous habit, their bulbose base appearing an- 

 nually from thickened rootstocks, their shortlived leaves, and their 

 inflorescence. They -differ from Polianthes in having their flowers soli- 

 tary instead of in twos, but in this respect they agree with one or two 

 reputed species of Bravoa (/>. sincjulijfora and B. densiflora). I have 

 studied seedlings of only one species, but have no doubt that the 

 development of all is similar. In the species studied a true bulb was 

 formed the first year. In the case of several species which I collected 

 in Mexico I found that the flowering stalks came from bulbs crowning 

 short rootstocks. In the case of Agave a true caudex is developed 

 the first year, which persists throughout the life of the plant. 



Unfortunately little attention has been paid by collectors to those 

 parts of the plant which grow beneath the surface of the ground, and 

 as a result many erroneous statements have crept into print. For 

 instance, in the original description of Prochnyanthes it is stated that 

 it has a " short, thick, erect bract-covered eaudex, v and in another part 

 of the same description it is said to have a " short caudex covered 

 with broad clasping leaves,' 1 while Bravoa is said to have the "root- 

 stock tuberous" and some species to have the "tubers oblong, with 

 tunics slitting into fine fibers at the top," 1 etc. 



In Mexico, where I examined many specimens, I found practically 

 the same structure in the ground parts of Bravoa, Prochnyanthes, 

 Polianthes, and Agave § Manfreda. A description of Prochnyanthes 

 is a description of all the others except in some minor details. In this 

 genus I found: 



(1) That the rootstock is small and covered with small bracts. (In 

 some species of Agave this rootstock becomes of great size, and it is 

 that which furnishes much of the amole of the Mexicans.) 



(2) That from the rootstock descend a number of spindle-shaped 

 fleshy roots. 



(3) That the rootstock is crowned by a well-developed tuber with 

 regularly concentric layers, and the top of the tuber crowned with a 

 cluster of fibers, which are the remains of the old leaves. 



] Hartweg (Trans. Hort. Soc. 3: 117, 18-18) speaks of one of these plants as follows: 

 "The soap plant, Agare xapoiutria, was found throwing up its tlower stem like a 

 tuberose, to whith, in fact, it hears much resemblance." 



