Rheum alexandrae is a perennial in the knotweed family (Polygonaceae) valued for ornamental use in borders and water gardens. It originates from south-west China and flowers in the UK from June to July. Planting and handling require care because all parts are harmful if eaten; wear gloves and protective equipment when working with it.

Alexander's rhubarb (Rheum alexandrae) is a perennial for partial shade and moist, acidic to neutral soils, flowering in the UK from June to July.

Rheum alexandrae

Alexander's rhubarb | Rheum alexandrae

Rheum australe is a perennial herb native to the Himalayas that can reach about 3.0 m in height. It flowers in the UK from June to July. Plant it in full sun on loamy or clay soils that remain moist but drain well. Parts are harmful if eaten, so wear gloves and protective equipment when handling.

Himalayan rhubarb (Rheum australe) is a tall perennial that flowers June to July and prefers full sun on moist, well-drained loamy or clay soil.

https://en.wikipedia.org/wiki/Rheum_australe

Rheum australe

Himalayan rhubarb | Rheum australe

Rheum officinale is a perennial herb in the Polygonaceae that reaches around 2.0 m and produces prominent flowering stems in June to July. It prefers full sun on loamy or clay soils that remain moist but are well drained. Rated H6 (very hardy) it will tolerate typical UK winters across much of the country. Allow generous space for its height when siting it in a border or specimen position.

Chinese Rhubarb (Rheum officinale) is a perennial to 2.0 m that flowers in June–July and prefers full sun with moist, loamy or clay, well-drained soil.

https://en.wikipedia.org/wiki/Rheum_officinale

Rheum officinale

Chinese rhubarb | Rheum officinale

Rheum palmatum is a tall perennial herbaceous plant in the knotweed family that can reach about 3.0 m. It is native to China and Vietnam and flowers in the UK from June to July. Plant in full sun on loamy or clay soils that remain moist but are well drained. Harmful if eaten; wear gloves and other protective equipment when handling.

Chinese rhubarb (Rheum palmatum) is a tall perennial that flowers June to July and suits moist, loamy or clay soils in full sun.

https://en.wikipedia.org/wiki/Rheum_palmatum

Rheum palmatum

Chinese rhubarb | Rheum palmatum

Rheum palmatum 'Atrosanguineum' is a perennial Rheum grown as an architectural, tall-stemmed specimen reaching about 3.0 m. It flowers in June to July and is valued at the back of large borders or as a single focal plant. Originating from China and placed in the Polygonaceae family, it prefers full sun on moist, loamy or clay soils. Wear gloves and other protective equipment when handling, as the plant is harmful if eaten and can be dangerous to pets.

Rhubarb 'Atrosanguineum' is a tall Rheum perennial from China that flowers in June to July and prefers full sun with moist loamy or clay soil.

Rheum palmatum 'Atrosanguineum'

Rhubarb 'Atrosanguineum' | Rheum palmatum 'Atrosanguineum'

Rheum palmatum 'Bowles' Variety' is a perennial in the knotweed family that reaches about 3.0 m and produces tall flowering stems above large palmate leaves. It flowers in June to July, with pink blooms presented on erect panicles. Plant in full sun on loamy or clay soils that remain moist but well-drained and expect it to tolerate UK conditions down to H6 (very hardy).

Rhubarb (Rheum palmatum 'Bowles' Variety') is a perennial to 3.0 m with pink flowers in June–July, best in full sun on moist loamy or clay soils.

Rheum palmatum 'Bowles' Variety'

Rhubarb | Rheum palmatum 'Bowles' Variety'

Rheum palmatum tanguticum is a perennial in the Polygonaceae that reaches about 2.0 m and is cultivated as an ornamental for borders. It flowers in June to July, producing pink blooms above the foliage. Plant in full sun on loamy or clay soil that stays moist but drains freely. Wear gloves and other protective equipment when handling because the plant is harmful if eaten.

Tangut rhubarb (Rheum palmatum tanguticum) is a fully hardy perennial to 2.0 m from China that flowers in June–July and suits sunny, moist loamy or clay.