SUPPOSED ALTERNATION OF FUNCTION IN PALMS. 117 



characters, tliat M. Gay proposed that it should have a genus to itself. 

 This concludes my review of the known species. 



SUPPOSED ALTERNATION OE FUNCTION IN PALMS. 



Directly on the appearance of the August number of the ' Journal 

 of the Linnean Society of London' (1869), I read with great interest 

 the paper of Dr. Eichard Spruce on the Palms of the Amazon, but I 

 did not take particular notice of § 15 (pp. 94 and 95), containing re- 

 marks founded upon observations which I hold to be erroneous, and 

 which are opposed to my own. 



[" Alternation of Function in, Palms. — I first ascertained its existence 

 when at San Carlos del Rio Negro, near the debouchure of the Casi- 

 quiari, in this way. In May, 1853, I found a small plot of ground 

 in the forest covered with plants of a delicate Palm, a species of Geo- 

 noma, growing about 10 feet high. The plants were all females, and 

 bore young fruits. On revisiting the spot in the same month of the 

 following year, I saw, to my astonishment, the very same plants all 

 bearing male flowers alone ! But the mystery disappeared when, on 

 examination, I made out that male and female spadices must have al- 

 ternated all the way up the stem. Afterwards I found that the same 

 or a similar alternation of function existed in many other Palms, and 

 that plants exercising (^pro tern.) the male function stood rarely far 

 apart fi-om others exercising the female function. The following are 

 the types of alternation that have fallen under my notice : — 



? ~ (^ in Geonoma discolor and other species. 



$ ~ $ (^ in C panicnligera, chelidonnra, etc. 



(J ~ ? (5* in Maocimiliana rerjia and some other Palms. 

 It is quite possible that extended observation might disclose the exis- 

 tence of all these modes of alternation in one and the same species ; 

 and I suppose that they must all be regarded as intermediate steps 

 towards that complete dioicity which many species of Palms have 

 already attained. It is easy to conceive how this change of function 

 may operate as a kind of repose to the plant, whose energies will be 

 less severely taxed when every alternate year (or season) it is relieved 

 from the burden of maturing the fruit. In species that have (appa- 

 rently) become permanently dioecious, it is curious to note how the 



