39° 



POPULAR SCIENCE MONTHLY. 



always has a straight trunk; 

 the clambering species never 

 have the trunk straight, and 

 the full-grown coco palms have 

 the trunk somewhat crooked. 

 A singularity of the growth of 

 palm trunks is that, with the 

 exception of the 'bellied' 

 trunks, they attain their full 

 diameter while quite young — 

 before, indeed, they set out to 

 grow upwards. In other words, 

 a palm grows endwise, as it 

 were, but does not grow in 

 diameter like the exogenous 

 plants. It is therefore neces- 

 sary that a palm should start 

 on a broad base if it is to reach 

 great height and great size. 

 For this reason many of them 

 when young look as if their 

 fronds were growing from the 

 top of a gigantic turnip-like 

 stock. In some species as a 

 trunk grows older it constantly 

 strengthens its foundations by 

 putting out rootlets just above 

 the uppermost ones, very much 

 like those starting from the 

 lower joints of a cornstalk, and 

 these roots continue to put 

 forth until a compact and exceedingly tough support is built up about 

 the trunk. In the pa^iulja palm this buttress is one of the strange 

 sights of the vegetable world. 



f- C^ '/ ( i 



Fig. 7 shows the remark- 

 able rooting of the paxiuha 

 (Iriartia exorrhiga). At the 

 lower left side of the plate the 

 details of one of these trunks 

 are shown. These palms seem 

 literally to be off the earth, for 

 the trunk proper can scarcely 

 be said to touch it. The figure 

 in the upper left hand corner 

 shows how the young paxiuha gets its start 



Fig. 3. 



Iriariea ventricosa, a Bellied Palm (Af- 

 ter Wallace). 



Fig. 4. Variations in the Form of the Trunk of 

 Bocadja, Asuncion, Paraguay. 



