Decodon verticillatus is a clump-forming wetland shrub with arching stems that can root where they touch soft mud. It bears rose-pink flowers along the stems and flowers from July to September. Native to eastern Canadian provinces, it occupies swampy ground and shallow water. It is used where standing wet, acidic soils need perennial woody cover.

Swamp loosestrife (Decodon verticillatus) is a wetland shrub for pond margins and wetland restoration that flowers from July to September.

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

Decodon verticillatus

Swamp loosestrife | Decodon verticillatus

Lagerstroemia indica With Love Eternal ('Milavio'PBR) (With Love Series) is a cultivated form of Lagerstroemia indica, a multi-stemmed, deciduous tree valued for its summer flower panicles. It blooms July to September. The bark is thin, pinkish‑grey and peels each year, while leaves turn yellow, orange and red in autumn before falling.

Crape Myrtle (Lagerstroemia indica With Love Eternal) flowers July to September and shows peeling pinkish‑grey bark and autumn leaf colour.

Lagerstroemia indica With Love Eternal ('Milavio'PBR) (With Love Series)

Crape Myrtle (Lagerstroemia indica With Love Eternal)

Lagerstroemia subcostata is a deciduous tree in the family Lythraceae, native to Japan, the Ryukyu Islands, Taiwan and southern China. It is recognised at least at the variety level, with var. fauriei recorded from Yakushima, Tanegashima and the Ryukyus and var. subcostata across the species range. In the UK it flowers from July to September. Crosses between var. fauriei and Lagerstroemia indica produced the hybrid Lagerstroemia × egolfii, which has yielded numerous cultivated forms.

Taiwan Crepe Myrtle (Lagerstroemia subcostata) is a deciduous East Asian tree that flowers in the UK from July to September.

Lagerstroemia subcostata

Taiwan Crepe Myrtle (Lagerstroemia subcostata)

Lawsonia inermis is an evergreen small tree in the Lythraceae with a multi-branched habit. It is sold under names such as Egyptian privet, henna and Jamaica mignonette. Best grown in full sun on neutral loam, it offers seasonal interest through spring and summer. Plant it in a south-facing, sheltered spot for use as a hedging or screening species.

Camphor (Lawsonia inermis) suits south-facing, sheltered hedges and screens and prefers full sun on neutral, moist but well-drained loam.

Lawsonia inermis

Camphor (of the Bible) | Lawsonia inermis

Lythrum salicaria is a perennial herbaceous plant in the Lythraceae, notable for its purple flowers. It typically reaches around 1.0 m in height and flowers from July to September. It prefers full sun and seasonally damp ground. It will tolerate a range of soils from sandy to clay provided they remain moist or wet.

Purple loosestrife (Lythrum salicaria) flowers from July to September and suits full sun in moist or wet sandy, loamy or clay soils.

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

Lythrum is a genus of 38 species of flowering plants native to the temperate world. Commonly known as loosestrife, they are among 32 genera of the family Lythraceae.

Lythrum salicaria

Purple loosestrife | Lythrum salicaria

Lythrum salicaria 'Brightness' is a perennial that produces upright spikes of purple flowers. It typically grows to about 1.0 m and flowers in summer. Plants suit sunny positions and tolerate a range of soils from sand to clay. They prefer consistently moist or wet ground but will also grow in moist, well-drained sites.

Purple Loosestrife Lythrum salicaria 'Brightness' produces upright purple flower spikes from July to September and suits sunny, moist soils.

Lythrum salicaria 'Brightness'

Purple Loosestrife | Lythrum salicaria 'Brightness'

Lythrum salicaria 'Firecandle' ('Feuerkerze') is a perennial in the Lythraceae that carries purple flowers and reaches about 1.0 m. It flowers July to September. Plant in full sun in sandy, loamy or clay soils that are moist or wet yet can be well drained. Fully hardy in the UK (H7) and suited to USDA zones 3–10.

Lythrum salicaria 'Firecandle' ('Feuerkerze') bears purple flowers from July to September and suits moist, full-sun sites.

Lythrum salicaria 'Firecandle' ('Feuerkerze')

Purple Loosestrife | Lythrum salicaria 'Firecandle' ('Feuerkerze')

Lythrum salicaria 'Morden's Pink' is a perennial loosestrife cultivar that produces upright stems to about 1.0 m bearing spikes of flowers from July to September. It grows best in full sun and tolerates sandy, loamy or clay soils that remain moist or wet. Fully hardy (H7, USDA 3–10), it suits damp borders, wet ground and naturalising in suitable sites. Plant where summer-to-early-autumn flower spikes are needed for structure and continuity.

Morden's Pink Loosestrife (Lythrum salicaria 'Morden's Pink') flowers from July to September and suits moist borders, wet areas and naturalising sites.

Lythrum salicaria 'Morden's Pink'

Morden's Pink Loosestrife | Lythrum salicaria 'Morden's Pink'

Lythrum salicaria 'Robert' is a perennial in the Lythraceae that forms upright stems to about 1.0 m bearing vertical spikes of purple flowers. It flowers from July to September. Plant in full sun on moist soils ranging from sandy to clay; it is fully hardy in the UK (H7).

Purple Loosestrife 'Robert' (Lythrum salicaria 'Robert') produces purple flower spikes from July to September and suits damp borders and water gardens.

Lythrum salicaria 'Robert'

Purple loosestrife 'Robert' | Lythrum salicaria 'Robert'

Lythrum salicaria 'Swirl' is an herbaceous perennial in the Lythraceae grown for its upright spikes of purple flowers. It forms clumps of deciduous foliage and flowers from July to September. Suited to full sun and moist soils, it tolerates both well-drained and poorly drained conditions. The cultivar performs well in south- or west-facing positions in exposed or sheltered sites.

Purple Loosestrife (Lythrum salicaria 'Swirl') produces purple flower spikes from July to September and suits moist, south- or west-facing borders.

Lythrum salicaria 'Swirl'

Purple Loosestrife | Lythrum salicaria 'Swirl'

Lythrum virgatum 'Dropmore Purple' is a clump-forming perennial in the Lythraceae with deciduous foliage that flowers in mid to late summer. It favours a sunny position and tolerates a range of soils from clay to loam, including damp or poorly drained ground. Fully hardy in UK gardens (H7), it reliably produces season-long blooms from July to September. Plant it where its upright summer inflorescences can be seen from paths or borders.

Lythrum virgatum 'Dropmore Purple' is a clump-forming loosestrife for full sun, flowering July–September and suited to clay or loam and damp soils.

Lythrum virgatum 'Dropmore Purple'

Wand Loosestrife | Lythrum virgatum 'Dropmore Purple'

Lythrum virgatum 'Rose Queen' is a perennial in the Lythraceae grown for summer flowering and use in borders, water gardens and as a cut flower. It favours full sun or partial shade and soils that remain moist yet well-drained, across acidic to alkaline pH. Rated H5 (hardy), it suits many parts of the UK and flowers from July to September.

Lythrum virgatum 'Rose Queen' is a perennial loosestrife for moist, well-drained soils that flowers July to September.

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

Lythrum virgatum 'Rose Queen'

Purple Loosestrife | Lythrum virgatum 'Rose Queen'

Lythrum virgatum 'The Rocket' is a perennial wand loosestrife selected for its erect summer flower wands. It suits any moist site and tolerates a wide range of soil pH. Plant in full sun or partial shade where soil remains damp but not waterlogged. Expect blooms from July to September.

Wand Loosestrife 'The Rocket' is a hardy perennial for moist borders and pond edges, flowering July to September.