50 ROBINSON : SPINES OF FOUQUIERIA 
Fouguieria to test the effect of changed climatic conditions upon it, 
but it has been observed that in greenhouses the leaves remain 
attached to the plant a number of months, while in nature they are 
usually cast off at the end of a few weeks ; and in some years, in 
the wild state, no leaves are produced. Lothelier’s experiments 
upon the barberry (Rev. Gén. Bot. 2: 276. 1890) showed that 
when grown in moist air it loses its spines. _Henslow (Jour. Linn, 
Soc. Bot. 30: 223. 1895) has madea similar observation for Oxomts 
spinosa, one variety of which living upon sandy shores is covered 
with spines, but becomes less and less spinose in favorable condi- 
tions or under cultivation, and he cites the cultivated apple and 
pear as similar examples. Miss Dale (Ann. Bot. 15: 59, 497- 
1901) has noted that when tubers of Droscorea sent out shoots in 
light and without moisture, the leaves were scarcely developed at 
all, and the same thing may now be observed in the Museum of 
the New York Botanical Garden, where tubers of Dioscorea in the 
exhibition cases have sent out branches, the leaves of which are — 
greatly reduced. 
There is a wide gap between Fouguieria and Cantua, its neat- — 
est relative among the Po/emoniales, which fact together with the 
small number of species in the genus, its confinement to a limited — 
area, and its stability may be taken to indicate that it is an old 
form, though there is no geological record so far as is known of — 
any similar spine-bearing form. 
