palm trunks are smooth while others are thickly covered with repulsive spines often of enormous size, and still others are clothed with mats of long tough fiber resembling masses of tangled and broken twine.
Certain species have trunks of uneven size, swollen here or there. These bellied palms, as they are called in Brazil, usually have the swollen part at some fixed place in the trunk. This is true of the paxiuba barriguda (Iriartea ventricosa) and of the Acrocomia, but at Assuncion, Paraguay, I found the swollen portions of the trunk of a palm locally called Bocadjá now near the base and now near the summit and another time near the middle. Some palm trunks are as smooth as if tooled, others, like the coco, are more or less ribbed. These ribs run round the trunk, and on some trees they are so close together that the whole trunk is notched with them. The ribs are really only leaf scars.
and on some species they are so far apart that the stems appear to be jointed like a bamboo. The ribbed trunks and smooth trunks, however, are noticeable only on palms that shed their fronds freely after they mature. In some cases the petiole breaks off two or three feet from the trunk, leaving it bristling with the jagged stumps of the petioles. In the accompanying illustration of the jupaty it will be seen that both conditions sometimes prevail with the same species.
Some trunks are thickly covered with spines. These spines vary in size from a few millimeters to half a meter in length. They seldom grow on the leaf scars, but usually cover the spaces between them.
Palm trunks may be either straight or crooked, but the habit of a species in this respect is pretty constant. For instance, the royal palm