The great branches of the tree held it up many feet from the ground at the point selected, and it was Sam's purpose to make the trunk the front of his house, building behind it, and having the fire in front.

The lower part of the trunk was high enough from the ground to let all the boys, except Sid Russell, pass under without stooping; Sid had to stoop a little.
The fire blazed presently, and by the time that Sam had his ditch done the boys began to come in with loads of cane and palmetes.

The palmetes are plants out of which what we call "palm-leaf fans" are made.

They grow in bunches right out of the ground in many southern swamps.

Each leaf is simply a palm leaf fan that needs ironing out flat, except that the edge consists of long points which are cut off in making the fans.
Sam cut two forked sticks and drove them in the ground about ten feet from the fallen tree trunk, and about ten feet apart.