Ornamental grasses that grow in clumps vary in form from stiff and upright to relaxed and floppy. When classifying grasses by form only the foliage is considered, not the flowering stems. Likewise, height is not a factor but the shortest grasses tend to be clumping while the tallest tend to be upright and arching. Most grasses can be classified in one of six groups but, of course, some grasses may fall somewhere in between. Varying the forms of the grasses planted together in the garden is one way of introducing variety into a planting and can add excitement and interest to the garden.
Slender spiky leaves emerge from a basal clump.
Example: Blue fescue (Festuca cinerea)
Relaxed clump the center leaves weeping over outer ones.
Example: Fountain grass (Pennisetum alopecuriodes)
Leaves are upright, often columnar.
Example: Cattail (Typha latifolia)
Stiff or erect leaves growing up and out.
Example Blue oat grass (Helictotrichon sempervirens)
Leaves upright as the emerge from clumpm becoming arching as they ascend.
Example: Silver feather maiden grass (Miscanthus sinensis ‘Silberfeder’)
Upward and outward spread of foliage about equal.
Example: Palm grass (Setaria palmifolia)