 The genus Persicaria is found within the family Polygonaceae along with other notable genera such as Rheum (Rhubarb), Rumex (Sorrel), Fallopia and Polygonum. In fact, until quite recently both Persicaria and Fallopia were included within Polygonum. Moving them into their own genera has led to some short term confusion but the new classification makes a lot of sense when one is thinking about the habits of various plants. For many excellent reasons Polygonum has developed a reputation for invasiveness and many of its species appear on banned or ‘not recommended’ lists. Some Persicaria can also be overly aggressive so it is wise to take care, but the plants described below are all great garden plants that work well in either domestic or commercial landscapes.
The attributes that make a great landscape plant, vigor, longevity, great foliage and long-lived showy flowers are well represented with these plants. Unfortunately Persicaria are often overlooked and underused in favor more flamboyant and well known genera such as Hemerocallis or Hosta. Don’t make that mistake, give these hardworking, beautiful plants the attention they deserve.
Several common names have been applied to members of this genus including Knotweed, Smartweed, Pinkweed, Bistort and Fleeceflower. The name Polygonaceae is thought to originate from the Greek for ‘many’ (poly) ‘knees’ (gonu) a description of the numerous joints or angled nodes to be found on the stems. Many Persicaria exhibit this interesting characteristic along with large, and often interesting, leaves produced one per node in an alternating pattern. Easy to grow, especially in a moist site such as near a pond or stream, Persicaria do not generally like to dry out, often going dormant if conditions become too dry. Full sun is preferred but a shadier location will work especially if there is a shortage of water, however blooming will likely be reduced. Flowers are usually terminal racemes in pink or creamy white and held on long stalks well above the foliage. The plants are easy to grow, with few pests or disease problems. Great for the beginner or a busy landscape contractor who wishes to minimize maintenance requirements. Generally considered to be resistant to predation by both deer and rabbits, while attracting butterflies, they are also excellent cut flowers.
P. amplexicaulis ‘Firetail’ (Mountain Fleeceflower) A great cultivar for filling in a large area with an easy care, showy plant. ‘Firetail’ needs room to spread out, easily forming a clump 3’ – 4’ (90cm – 120 cm) across, with similar height, when in bloom. But it is not invasive. Once it reaches this size its growth rate slows dramatically and it is not going to carry on to explore the rest of the garden. The leaves are best described as arrow head shaped and can easily reach a foot (30 cm) in length. ‘Firetail’ will provide a show of crimson-red flower spikes from mid summer until frost. Each spike can reach a length of 6” (15 cm) with numerous spikes per plant. This plant is used successfully in commercial and park landscapes and is a great addition to a larger garden. USDA 3 - 9
P. bistorta ‘Superba’ (Knotweed or Bistort) A somewhat more subtle show is provided by this cultivar that has been granted a RHS (Royal Horticultural Society) award of garden merit (AGM) due to its superior garden performance. The flowers are a pale, but vibrant, pink and are held on short spikes just above the foliage. Plants will reach a height of about 2’ (72 cm) and will spread to about 3’ (100 cm). Once again, a great landscape plant that expertly walks the line between being vigorous enough to be an excellent ground cover, but restrained enough not be, in any way, invasive. USDA 3 – 9
P. filiformis ‘Painter’s Palette’ (European Bistort) This excellent plant is a departure from the other cultivars described herein, as it is grown for its wonderful foliage, while its flowers are not particularly showy. The leaves are a refined 3” – 4” (7cm – 9 cm) in length and are beautifully mottled with cream against a green background offset with a distinct dark brown chevron just past the midway point. This provides a wonderful bright show for a shady area. ‘Painter’s Palette’ tends to be somewhat more tolerant of dryer sites making it a good contender for ground cover under deciduous trees. The flowers are tiny, red and held aloft on spikes from July through August, but are pretty much lost against the foliage display. Some self-seeding can occur and the plants will spread slowly via their rhizomes, but again not invasively, just a great ground cover. Height: 2’ – 4’ (60 cm – 120 cm) Spread: 12” – 24” ( 30 cm – 60 cm). USDA 3 – 9
P. polymorpha (Giant Fleeceflower)
A little known and very much underused herbaceous perennial that has the garden presence of a small shrub. Dieing back to the ground each year but rapidly reaching heights of 5’ – 7’ (150 cm – 200 cm) with extremely showy, creamy white fluffy plumes of flowers that last for months and are followed by attractive seed heads. With its great upward growth it is understandable for one to be concerned about the vigorousness of any horizontal spreading. But there is absolutely no need for concern. It will sit quite happily in its assigned location, slowly increasing in clump size (2’ – 3’, 60 cm – 100cm) at about the same rate as a Paeonia would — nothing to be apprehensive about. In addition self-seeding is not an issue — the ten year old specimen in my garden has yet to produce a seedling. This is a beloved plant of the great landscape designer Wolfgang Oheme, who will often introduce landscape designers to his favorites in an effort to see them gain greater prominence and use. Deserving of the moniker ‘architectural specimen’, this easy to grow plant will make a statement in any garden, residential or commercial. USDA 5 – 9 |
