Persicaria is a genus of perennial flowers that thrives throughout temperate zones. There are a number of distinct species within the genus, but many share the same tall, leafy stalks and clusters of small flowers. Flowers come in a variety of colors that can make them a desirable addition to home landscapes, but some members of the genus can be an invasive species. As they spread via the reproduction of rhizomes, species such as the Japanese knotweed can quickly take over a garden.
Belonging to the family polygonaceae and native to parts of Asia that include Japan and China, these tall plants are known for their clusters of flowers and long blooming time. Many varieties of Persicaria will bloom throughout the summer months, when they sport clusters of flowers that can be up to 6 inches (about 15 cm) long. The non-invasive species can be highly prized by gardeners, as they can grow to sprawling clumps between 3 and 4 feet (about 0.9 to 1.2 m) tall and just as wide.
Most varieties have long stems with slender, spear-shaped leaves of varying shades of green. Some, like the firetail, are dark green while others, such as the golden arrow variety, are pale, yellowish-green. Others, such as the Japanese knotweed, have rounder leaves that are variegated and different shades of green. The colors of the flowers also depend on the species and the cultivar, and can be found ranging from whitish-green to dark red and pink.
Some cultivars of native Persicaria flowers have been created in an attempt to eliminate the invasive properties of the plant while keeping the desirable characteristics. The firetail cultivar of the Persicaria mountain fleece and the alba varieties do not spread as much as other varieties, and still retain the long, slender leaves and clusters of bright flowers. Some have been created as low-lying ground cover, such as the dimity and the superba; these cultivars do not reach the heights of other varieties, but still have the same distinctive spikes of flowers.
Plants of the Persicaria genus can typically thrive in a wide variety of conditions, from sunny areas to shade and dry to wet soils. Most will spread more and grow taller when exposed to moist, partially sunny conditions, but they can tolerate and adapt to less than perfect locations. In some areas, flowers can be seen blooming well into the cooler fall and early winter months. As garden plants, they can be highly desirable for those individuals who want to draw butterflies and some kinds of wild birds to the yard.