The Bio-Process Group has been developing high quality paper pulps from a variety of dedicated fast growing biomass crops.
Bamboo is a very hard substrate which can be converted to a nice high quality long fibered pulp.
Miscanthus is a fast growing grass identified as a possible 'high producing biomass' for celluosic ethanol, but also produces a nice pulp.
Arundo is a fast growing cane type biomass which can be harvested several times a year under correct growing conditions. It also makes a nice pulp as per photos below.