 Somewhere between 29 and 67 species are recognised in the genus , with estimates of as many as 100 . <unk> <unk> collections make it difficult to determine whether certain groups represent single species , or groups of similar species . <unk> species have a long history of human use , and include economically important sources of palm oil and fibre . Many species are fire tolerant and thrive in disturbed habitats . Their seeds are animal dispersed , including some which are thought to have been adapted for dispersal by now @-@ extinct Pleistocene <unk> . 
