Polygonum albinum is a perennial in the knotweed family that can grow as a mat-forming ground cover, a clump, or as tall upright stems. It has deciduous, simple leaves that range from lance-shaped to heart-shaped and are often marked or take an autumn tint. Flowering occurs from July to September. Plants tolerate a wide range of soils, including heavy clay, and are suited to full sun or partial shade.

Knotweed (Polygonum albinum) is a perennial Polygonaceae species flowering July to September that tolerates full sun to partial shade and most soils.

The knotweeds are vigorous, long-flowering plants carrying dense narrow spikes or loose sprays of tiny flowers, usually in pink, crimson or greenish white, above simple lance-shaped or heart-shaped foliage that frequently colours well in autumn. Habit varies enormously, from low creeping mats that make dense weed-suppressing cover to tall, architectural clump-formers. Several are extremely vigorous, and the genus has been extensively reclassified, with many garden plants now placed in Persicaria.

Polygonum albinum

Knotweed | Polygonum albinum

Polygonum carneum is a perennial in the buckwheat family (Polygonaceae) that can grow as a mat-forming ground cover, clump, or a taller upright plant. It has deciduous, simple leaves that range from lance-shaped to heart-shaped and may be marked or take on autumn tints. Flowering occurs from July to September. It suits a wide range of positions and soils, and prefers reliably moist conditions.

Knotweed (Polygonum carneum) flowers from July to September and suits moist, any-soil sites in full sun or partial shade.

Polygonum carneum

Knotweed | Polygonum carneum

Polygonum equisetiforme is a perennial knotweed that can form mats, clumps or grow upright to about 1.0 m. It has deciduous, simple leaves that range from lance-shaped to heart-shaped and are often marked or take on autumn tints. Flowering occurs July to September. It suits a wide range of sites, including heavy clay and damp ground.

Knotweed (Polygonum equisetiforme) is a perennial from Portugal that reaches about 1.0 m and flowers July to September.

Polygonum equisetiforme

Knotweed | Polygonum equisetiforme

Polygonum milletii is a perennial member of the buckwheat family (Polygonaceae) that can grow as a mat-forming ground cover, clump-forming plant or as a taller upright perennial. The leaves are deciduous, simple and range from lance-shaped to heart-shaped, often showing markings or autumn tint. It flowers from July to September. It tolerates a wide range of soils, including heavy clay, and prefers moist conditions.

Polygonum milletii is a perennial knotweed that flowers July to September and suits moist soil in full sun to partial shade.

Polygonum milletii

Knotweed | Polygonum milletii

Polygonum paniculatum is a perennial member of the buckwheat family (Polygonaceae) with a notably variable habit: it may be mat-forming, clump-forming or grow tall and upright. Leaves are deciduous, simple and range from lance-shaped to heart-shaped, often marked or taking on autumn tint. It prefers full sun to partial shade and tolerates almost any soil, including heavy clay, as long as the ground remains reasonably moist. Flowers are produced from July to September.

Knotweed (Polygonum paniculatum) is a perennial that flowers from July to September and tolerates moist soil and heavy clay.

Polygonum paniculatum

Knotweed | Polygonum paniculatum

Polygonum regelianum is a perennial knotweed that shows a notably variable habit, from mat-forming and clump-forming to taller, upright growth. Its deciduous leaves are simple, lance-shaped to heart-shaped and are often marked or take on autumn tints before falling. Flowering occurs July to September. It tolerates a wide range of soils, including heavy clay, and prefers reliably moist conditions over drought.

Knotweed (Polygonum regelianum) is a perennial with variable habit that flowers July to September and suits moist soils in full sun to partial shade.

Polygonum regelianum

Knotweed | Polygonum regelianum

Polygonum rude is a perennial in the knotweed family with a variable habit that can be mat-forming, clump-forming or tall and upright. The foliage is deciduous, simple and ranges from lance-shaped to heart-shaped, often marked or taking on autumn tints. It flowers from July to September. Plants tolerate almost any soil, including heavy clay, and prefer moist conditions in full sun to partial shade.

Knotweed (Polygonum rude) is a deciduous perennial that flowers July to September and thrives in moist soils, tolerating heavy clay in sun or part shade.

Polygonum rude

Knotweed | Polygonum rude

Polygonum ussuriense is a perennial knotweed that can be mat-forming, clump-forming or grow tall and upright. Its deciduous leaves are simple, lance- to heart-shaped and are often marked or take on autumn tint. Flowering in the UK occurs from July to September. It tolerates full sun to partial shade and will grow in almost any soil, including heavy clay, provided the ground stays reasonably moist.

Knotweed (Polygonum ussuriense) is a deciduous perennial from northeast Asia that flowers July to September and tolerates heavy clay and moist ground.