Possible Clues:

• Sustainable crop with shoots
• Woody grass plant
• Largest member of the grass family
• It is actually a grass, not a wood
• Tropical grass/wood
• Reed evoked in 'Eats, Shoots & Leaves'
• Tropical grass with hollow stems
• Express disapproval about a medic supplying grass!
• Express disapproval about a doctor offering grass
• Cane makes graduate low after pinching book