Polygonum coriaceum

Position: Full sun to partial shade

Flowering period: Late summer to autumn

Soil: Moist, well drained

Eventual Height: 30cm

Eventual Spread: 40cm

Hardiness: 6a, 6b, 7a, 7b, 8a, 8b, 9a

Family: Polygonaceae

Polygonum coriaceum is a semi evergreen herbaceous perennial with a spreading habit. Polygonum coriaceum is native to south west China and Tibet. Polygonum coriaceum is synonymous with Bistorta coriacea. In its native habitat it grows on grassy slopes and forest edges. Its mid green leaves are up to 14cm long. Its pink flowers appear on terminal spikes and are attractive to pollinating insects. Its roots are rhizomes, which aids its spread. Polygonum coriaceum is not widely available commercially in the UK.

Polygonum coriaceum (20/10/12, Kew Gardens, London)

Polygonum coriaceum Flower (20/10/12, Kew Gardens, London)

Landscape Architecture

Rheum palmatum var. tanguticum

Rheum palmatum var. tanguticum (15/08/15, Kew Gardens, London)

Position: Full sun to partial shade

Flowering period: Late spring to mid summer

Soil: Moist, well drained to boggy

Eventual Height: 90cm (2m with flower spike)

Eventual Spread: 1.8m

Hardiness: 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b

Family: Polygonaceae

Rheum palmatum var. tanguticum is a deciduous herbaceous perennial with a clump forming habit. Its mid to dark green leaves emerge dark red, are orbicular or broadly ovate with pointed lobes and undulate margin, up to 60cm long and 60cm across. Its dark pink flowers appear on long stalks in the form of panicles and are wind pollinated. Its roots are rhizomatous.

Rheum palmatum var. tanguticum, commonly known as Chinese Rhubarb and Da Huang, is native to eastern Asia including northwest China. In its native habitat it grows by streams in scrub. Rheum palmatum var. tanguticum is synonymous with Rheum tanguticum var. tanguticum.

The etymological root of the binomial name Rheum is derived from the Persian rha, the name given the Rhubarb. Palmatum is from the Latin meaning ‘palm like’, in reference to the leaves. Tanguticum is from the Latin meaning  ‘of or from Tangut, Tibet’.

Rheum palmatum var. tanguticum Leaf (15/08/15, Kew Gardens, London)

The landscape architect may find Rheum palmatum var. tanguticum useful as a fast growing perennial with large architectural leaves, particularly in damp soils. It should be noted all parts of the plant are poisonous when ingested.

Ecologically, Rheum palmatum var. tanguticum is of little ecological value in the UK.

Rheum palmatum var. tanguticum prefers moist to boggy, humus rich, fertile soils. It prefers a neutral to acidic pH of soil. It will not tolerate dry soils.

Rheum palmatum var. tanguticum requires little maintenance. Large clumps may be divided in spring.

Landscape Architecture

Persicaria bistorta

Persicaria bistorta (23/06/2013, Kew Gardens, London)

Position: Full sun to partial shade

Soil: Well drained

Flowering period: Summer to early autumn

Eventual Height: 75cm

Eventual Spread: 90cm

Hardiness: 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b

Family: Polygonaceae

Persicaria bistorta Flower (23/06/2013, Kew Gardens, London)

Persicaria bistorta is an evergreen herbaceous perennial with a bushy habit. Its dark green leaves are narrowly ovate with entire margins and are up to 30cm long. Its pale pink flowers are funnel shaped and appear as dense spikes above the foliage and are up to 7cm long. Its roots are rhizomes which aids its spread.

Persicaria bistorta, commonly known as Bistort, Common Bistort or Adderwort, is native to Europe (including the UK) and north and west Asia.

The etymology of the binomial name Persicaria was a medieval name referring to the likeness of the leaves to a peach tree, Prunus persica. Bistorta is derived from the Latin bis meaning ‘twice’ and tortus meaning ‘twisted’, in reference to its roots.

Persicaria bistorta Leaf (23/06/2013, Kew Gardens, London)

Persicaria bistorta may be useful to the landscape architect as an effective low growing ground cover, particularly when planted en mas. It is suitable for planting on slopes or banks where low maintenance is required. This perennial is not attractive to deer or rabbits.

Ecologically, Persicaria bistorta flowers are attractive to pollinating insects.

The Royal Horticultural Society has given the variety Persicaria bistorta ‘Surperba’ their prestigious Award of Garden Merit in 1993.

Persicaria bistorta prefers moist, fertile, well-drained soils. It tolerates most pH of soil. It will tolerate poorly drained soils.

Persicaria bistorta requires little to no maintenance. Large clumps may be divided in spring or autumn.

Landscape Architecture