Bambusa / bamboo

• Bambusa multiplex 'Alphonse Karr' is a 15 to 25 foot tall bamboo that makes an effective garden screen. Punting Pole Bamboo and Giant Timber Bamboo grow even taller, and have thick stems suitable for timber harvest.
  
  

Phormium tenax / Flax

• While most named varieties of Phormium tenax have been cultivated for their small size in addition to their foliage color, many named varieties do get to 5 to 7 feet tall and serve as a strong garden backdrop or informal screen. 'Rainbow Chief' and 'Pink Stripe' will each reach 5 feet in five years, 7 feet in time.
  
  

Miscanthus sinensis / Maiden Grass

• Miscanthus sinensis is a fast-growing ornamental grass that is tall enough to make a summer windbreak or screen. M. sinensis 'Cabaret' is a white-striped grass which reaches 7 feet. M. sinensis 'Strictus' is a gold-striped grass to 8 feet tall.
  
  

Stipa gigantea / Giant Feather Grass

• Stipa gigantea has foliage to only 2 feet tall, but its feathery flower stalks reach 6 feet tall. It blooms in summer and holds its flower stalks until mid-winter, so is effectively a tall ornamental grass for half the year.
  
  

Calamagrostis x acutiflora 'Avalanche' / Feather Reed Grass

• Calamagrostis x acutiflora 'Avalanche' is a variegated plant that has foliage to 3 feet tall and blooming stalks to 6 feet tall. It is a fast-growing ornamental grass and becomes tall only during the growing season when it blooms.