The green form of Japanese blood grass (Imperata cylindrica) can indeed spread quite readily, and some states have outlawed planting it. The cultivar 'Red Baron', a form with red-tinged foliage, is generally well-behaved in the garden. If you plant it, be sure to remove any solid green shoots that develop. They can quickly take over the entire planting. Invasiveness of ornamental grasses often depends on location. An overachiever in one part of the country may limp along, scarcely surviving, in another. For example, pampas grass (Cortaderia selloana) is considered invasive in California, whereas gardeners in the Midwest have to struggle to grow it, because winters are too cold. Eulalia grass (Miscanthus sinensis) may self-seed in warm areas with long growing seasons, but in areas with shorter growing seasons it seldom produces viable seed. Cattails (Typha) may take over wetlands but will behave on drier sites. Grasses (and bamboos) with runners are almost always invasive. Ribbon grass (Phalaris arundinacea) and blue lyme grass (Leymus arenarius 'Glaucus') are examples of grasses that quickly spread in the landscape.