THE AMERICAN BOTANIST. 
51 
In northern California salal is but a few inches high. 
It gets taller as we go north, and at Vancouver, B. C. I 
saw where trails had been cut through solid masses of it, 
and the wall on each side was higher than a man's head. 
I separated out single stems that were more than eight 
CURIOUS DEVICES FOR PLANT PROTECTION. 
INTERESTING examples of self-protection are offered by 
several plants growing in Guam, the most striking ot 
which is the spin}- yam {Dioscorea spinosa). This plant 
grows spontaneously on the island and in places forms 
impenetrable thickets. It takes its name not from the 
small prickles on the stem but from a mass of spines sur- 
rounding the base of the stem and ser\nng as a protection 
to the starchy tul^ers below from hogs and other enemies. 
They are wiry and branching and have very much the 
appearance of sharp compound fish-hooks. In reality 
they are lateral roots which differ from typical mono- 
cotyledonous roots in their hard woody structure and the 
absence of root-caps. Whether or not these spines have 
been specially developed for the purpose of protecting the 
edible tuber 'may be questioned, but that they do protect 
Among the principal food staples of Guam is the taro 
(Caladium colocasia) a plant of the ^ram family. Both 
the land and water varieties are found to have their 
smooth, succulent, satiny leaves free from the ravages of 
snails, insects or herbivorous animals. Cattle ^ and 
chickens delight in nipping off the young leaves of bananas 
and plantains, deer often inflict serious injury on a young 
coconut plantation in a single night, breadfruit trees 
suffer from the attacks of all herbivorous animals and 
must be protected from them, fruit, leaves and bark, and 
even tobacco will be devoured in the field by insect larviE 
tinless it is carefully watched and tended. On chewing a 
portion of a taro leaf the cause of its safety from attack 
