We had to ascend the western precipice of Ccasa-sani by a frightful kind of ladder, formed of ledges in the rock, or half-rotten branches of trees, here and there having to cross a yawning chasm on the fallen stems of tree-ferns rotting from age. Near the summit we had a glorious view of the forest-covered mountains, running up into sharp peaks, with graceful palms rising above the other trees on their crests, and standing out against the sky. Several _Calisaya_-trees were growing on the summit, with bunches of young capsules, in company with the leathery-leafed _huaturu_, and the _Aceite de Maria_ (_Elæagia Mariæ_, Wedd.). The latter is a tree about thirty feet high, with bark covered with white lichens. Among the numerous ferns the most conspicuous was a very large _Polypodium_, called _calaguala_. Descending the rocks of Ccasa-sani, we had to continue the work of cutting our way through the forest, our passage being opposed by matted entanglements of bamboo, and a _Panicum_ with blades, the edges of which cut like a penknife, called _challi-challi_. On many of the trees there were hornets'-nests, globes of mud fixed to the leaves, and covered with the insects. I was inadvertently going to touch one, which was attached to the back of a large fern-frond, when Martinez, with great dexterity, hurled the plants down the precipice, before the savage creatures were aware of their danger. We were now in the midst of the chinchona region; and passed several trees of _C. ovata_ (_morada ordinaria_) and _C. micrantha_ (_verde paltaya_). There were also great quantities of a false chinchona, called by Martinez _Carhua-carhua blanca_. We passed through several large groves of this species, which appeared to be a _Lasionema_, but differed in several respects from the _L. chinchonoides_, mentioned by Dr. Weddell as growing in the Caravayan forests. The tree is very common near the banks of the river Tambopata, frequently with its boughs, large coarse leaves, and panicles of flowers, drooping over the water.[333]