Bistorta officinalis ‘Superba’

Bistorta officinalis ‘Superba’ is probably the second-most grown species in the genus, after the Bistorta amplexicaulis cultivars that have become popular with ‘New Naturalistic’ planting and are planted in large numbers.

The species itself, B. officinalis (formerly ‘Persicaria bistorta’ and ‘Polygonum bistorta’ before that), grows across Europe, tending to prefer higher altitudes in more southerly locations. Typically the species is naturally found growing in damp screes and alpine meadows; this is a cool climate plant. In cultivation B. officinalis ‘Superba’ tends to be grown more as a waterside plant in warmer and drier regions, but in cooler and damper areas it will grow happily as a border plant.

The spikes of pink flowers in spring are a delight, although the seeding that follows might be considered a nuisance in some plantings. Although the cultivar ‘Superba’ is considered a more refined and desirable form of the species it must be remembered that the cultivar is just one step away from the wild species, a plant that is used to fending for itself against competition; B. officinalis is not a good companion for delicate border plants!

Spikes of Bistorta officinalis ‘Superba’ with Digitalis purpurea in a wild garden

Our relationship with B. officinalis in the UK hasn’t always been just horticultural. In folk medicine the species has been used to make a tea to treat headaches, toothaches and urinary complaints, to aid conception, and as a vermicide (worm killer). In parts of Northern England particularly the young leaves of B. officinalis are still used in traditional ‘Easter Ledger Pies’, which contain a very broad range of ingredients depending on recipe; these pies were traditionally made at that awkward point in the year when the winter food supply was running low and before the new harvests were ready, with the early-emerging wild bistort leaves used to bulk out meagre rations of food. Such was the connection between people and this plant that there is a strong likelihood that it was deliberately introduced to graveyards as part of an effort to cultivate it conveniently.

So where did the cultivar ‘Superba’ actually come from? So far I’ve struggled to find an origin for this plant. Given that the plant comes true from seed, and seemingly has done for a very long time, I’m satisfied that it represents a naturally occurring variation in the species; taxonomically speaking there is an argument that says that it should in fact be Bistorta officinalis var. superba.

Bistorta officinalis ‘Superba’

Whatever the correct name for this plant I believe its appreciation in horticulture has come comparatively recently. In ‘Wild Flowers In The Garden’, a fascinating little book from the late 1940s or early 1950s (possibly 1951, but as the book has no publication date it’s impossible to be sure), Walter Ingwersen describes finding an exceptional form of what he was calling at that time ‘Polygonum bistorta’. Researching the Polygonaceae you soon get used to brief mentions of species, usually in passing as the author moves on to something else, so Ingwersen doesn’t really dwell on his selection for very long. Was this Bistorta officinalis ‘Superba’?

The earliest reliably dated mention of B. officinalis ‘Superba’ I’ve managed to find is a brief piece in The Gardener’s Chronicle from 1936.

“I have in mind an informally planted group of Polygonum bistorta var. superba in a shady woodland walk where the late afternoon sun was able to shine through the surrounding trees on to its long spikes of pink flowers, making a very pretty picture with the dark green background…”

A. Dennett of Kingsmoor Gardens, Sunningdale (UK). 7th of November 1936.

This is an interesting piece for a few reasons. Firstly it’s not introducing the species (the writer is already familiar with the plant under the name ‘Superba’), while secondly the name ‘var. superba’ is being used rather than the cultivar ‘Superba’. Thirdly the writer makes the excellent point that B. officinalis ‘Superba’ does well in sun or shade. I think it’s fairly sensible to say that B. officinalis ‘Superba’ was established in cultivation by 1936.

Bistorta officinalis ‘Superba’ as part of a ‘wild look’ grass planting

Despite its coarseness and self-seeding this plant has had its fans over the years, although it’s interesting to note that no great ‘plantsmanship’ author has really given B. officinalis more than passing praise.

“…Polygonum bistorta ‘Superba’, and although no one who values his peace would admit a knotweed to his garden without the most careful inquiries as to its credentials, this bistort does not offend. It is as courageous as the betony as a weed eliminator, and from its tufty carpet of dock-like leaves puts up twenty-inch red stems each terminating in a three-inch cylindrical head of pink blossoms. Here, then, is another ornamental plant which makes no clamour for attention and, incidentally, does us practical service as a labour saver.”

From ‘The Mill Garden’ by A.T. Johnson

Others have similar thoughts, and it seems that the majority of authors consider this to be around the right amount of text to devote to this plant. Knowing that this web page might actually represent the largest body of text about B. officinalis ‘Superba’ to reach the public domain makes me a little sad!

As I’ve suggested above, Bistorta officinalis ‘Superba’ is not a plant to plant idly. It seeds around a bit (as do other garden favourites like Verbena bonariensis) and spreads at the roots, forming a sizeable clump in a short time. I’m not going to say that this plant is ‘invasive’ because that wouldn’t be fair; instead I would describe this plant as being ‘vigorous, and potentially able to outcompete other garden plants’. This is a species that prefers higher rainfall and cooler temperatures, so it’s not unsurprising to hear that in warmer and drier conditions it’s considered better behaved than it is in cooler and wetter conditions. In rich soils with reliable moisture it can reach 60cm (2ft) in flower, but where soil is less rich and where moisture is reduced it can flower at a more modest 30-45cm (1ft to around 18”). In my region of the UK, where summer temperatures are rarely very high for very long and where rain is usually not far away, B. officinalis ‘Superba’ quickly makes robust clumps that densely cover the ground, while seedlings often appear in other areas of a garden and, if not monitored or removed, make new dense colonies. In a large garden this is a desirable trait, rewarding the frugal gardener with an abundance of flowers and weed suppressing foliage without much financial outlay, but in a smaller garden this plant can be become a nuisance.

I use B. officinalis ‘Superba’ fairly frequently in the larger gardens that I manage, occasionally in the borders but increasingly in areas of wet grass and in ‘wildflower gardens’. The plant seems quite at home, providing young plants are protected from invasive grasses in their first year or so. When planting into grass it’s best to lift a sensible area of turf and plant into bare soil. I would also recommend marking the positions of each plant for the first year in case they need watering; when the grass grows tall it’s nearly impossible to find little plants! Once established I do find that this species needs no further care.

Bistorta officinalis ‘Hohe Tatra’ in the trial bed, RHS Wisley, 2021.
Note the rather invasive Persicaria runcinata behind!

For smaller gardens there are sensible alternatives to using B. officinalis ‘Superba’. The first alternative is the eminently charming and beautiful B. officinalis ‘Hohe Tatra’, a collection of the species made on the mountain of the same name. This is the better form of B. officinalis for the absolute majority of gardens; its narrower leaves are a wonderful shade of green, its flowers are a richer colour and it makes a dense, tidy clump with no seeding. I’ve seen B. officinalis ‘Hohe Tatra’ described as “a garden-safe bistort”- very true! As with B. officinalis ‘Superba’ it can flower at around 60cm (2ft) tall in optimum conditions but will be shorter in drier or poorer soils.

Bistorta officinalis ‘Hohe Tatra’ in the foreground, with B. officinalis ‘Superba behind

While B. officinalis ‘Superba’ and B. officinalis ‘Hohe Tatra’ prefer cooler conditions, cooler and possibly even shaded conditions are crucial for success with Bistorta carnea. This species was formerly known as ‘Persicaria bistorta ‘Carnea’ but, under the recent taxonomic review, has now been elevated to its own species. This species, found in the higher areas of Eastern Europe and West Asia, makes a tight and diminutive mound of leaves, each silvery-white on the underside, and short stems with miniature heads of coral-pink flowers. It’s a delight and should be included in any self-respecting woodland garden, where moisture allows. In cooler and more northerly regions this plant will likely cope well in full sun, yet even here in Devon it prefers cooler and shadier parts of the garden. Slowly clumping and growing barely above 30cm (1ft) tall in perfect conditions, this is a bistort you can trust!

Bistorta carnea

Note: I’ve mentioned here that these bistorts need cooler and damper conditions, but it’s worth noting that all members of the genus Bistorta are plants of high altitude and are profoundly displeased by heat and drought. Most clones of B. amplexicaulis are more tolerant (the species is pretty robust to start with!) but even a superficially perfect plant can show signs of stress when you look more closely. The shallowly rooted species, B. affinis, B. emodi and B. vaccinifolium, are particularly susceptible to drought and heat, and in the wrong conditions will dry to a crisp!