Acanthus balcanicus is a herbaceous perennial valued for its architectural form. Native to the Balkans, it belongs to the Acanthaceae family and flowers from June to August. Plant in full sun or partial shade in moist, well-drained soil and expect hardy performance in most UK gardens (H5).

Bear's Breeches (Acanthus balcanicus) is a herbaceous perennial from the Balkans that flowers June–August and suits borders and architectural plantings.

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

Acanthus balcanicus

Bear's Breeches | Acanthus balcanicus

Acanthus spinosus is an herbaceous perennial that reaches about 1.5 metres and is valued for its summer flower spikes. Native to the Mediterranean, it flowers from June to August. It forms clumps 0.6–0.9 metres across and prefers well‑drained, fertile soil of neutral to alkaline reaction. Suited to full sun or partial shade and used in borders and architectural plantings.

Spiny bear's breech (Acanthus spinosus) is a hardy herbaceous perennial that flowers June to August and suits well‑drained, neutral to alkaline soils.

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

Acanthus spinosus

Spiny bear's breech | Acanthus spinosus

Acanthus spinosus spinosissimus is a herbaceous perennial in the Acanthaceae, notable for deeply cut leaves with spiny margins and erect flower spikes. It produces white flowers set against maroon bracts and flowers in the UK from June to August. It grows well in full sun or partial shade and prefers moist, well-drained soil. Often used where bold basal foliage and vertical flower stems are wanted.

Spiny Bear's Breech (Acanthus spinosus spinosissimus) is a herbaceous perennial with spiny, divided leaves and white flower spikes June to August.

Acanthus spinosus spinosissimus

Spiny bear's breech Spinosissimus Group | Acanthus spinosus spinosissimus

Pseuderanthemum carruthersii var. atropurpureum 'Rubrum' is an upright shrub prized for variegated foliage that shows green with areas of pink, purple or yellow. It flowers from July to October. Place it in full sun or partial shade on a south-facing, sheltered site in neutral loam that remains moist yet drains freely. Suitable for ornamental planting and containers and rated H4 (average) for UK conditions.

Pseuderanthemum carruthersii var. atropurpureum 'Rubrum' is an upright shrub with variegated pink, purple or yellow foliage that flowers July to October.

Pseuderanthemum carruthersii var. atropurpureum 'Rubrum'

Ruellia humilis Wild Petunia is a species of flowering plant in the Acanthaceae. It is a low-growing plant, typically about 0.3–0.6 m tall. The stems and leaves are covered with soft white hairs and the leaves are oppositely arranged. It is cultivated as an ornamental.

Ruellia humilis Wild Petunia flowers from July to October and is grown as an ornamental plant.

Ruellia humilis Wild Petunia

Wild Petunia | Ruellia humilis Wild Petunia

Sclerochiton odoratissimus is a flowering plant in the family Acanthaceae that produces blooms from July to September. It is recognised as a distinct species within the genus Sclerochiton. Detailed notes on flower colour, size and cultivation vary between species and individual plants. For identification or cultivation specifics consult specialist sources or supplier records before planting.

Sclerochiton odoratissimus is a member of the Acanthaceae that flowers in the UK from July to September.

Sclerochiton odoratissimus

Sclerochiton odoratissimus | Acanthaceae, flowers Jul–Sep

Strobilanthes atropurpureus is a species in the genus Strobilanthes, family Acanthaceae. Its primary seasonal feature in UK gardens is a summer display, flowering from July to September. Cultivation requirements vary between species and stock, so follow supplier or specialist guidance for planting and care. Prune only after the September flowering to avoid cutting next season's buds.

Strobilanthes atropurpureus flowers in the UK from July to September, so plan siting and pruning around its summer display.

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

Strobilanthes is a genus of about 350 species of flowering plants in the family Acanthaceae, mostly native to tropical Asia and Madagascar, but with a few species extending north into temperate regions of Asia. Many species are cultivated for their two-lipped, hooded flowers in shades of blue, pink, white and purple.

Strobilanthes atropurpureus

Thunbergia alata Sunny Susy Brownie ('Sumthun 04'PBR) (Sunny Susy Series) is a climbing, evergreen member of the Acanthaceae grown for its twining stems and summer flowering. It prefers full sun on a neutral loam with free drainage and a sheltered, south-facing aspect. As an H2 (half-hardy) plant it benefits from siting where frost exposure is limited or from winter protection under glass. It suits walls, containers and conservatory display.

Thunbergia alata Sunny Susy Brownie ('Sumthun 04'PBR) prefers full sun on neutral loam in a sheltered, south-facing spot and flowers June to October.

Thunbergia is a genus of flowering plants in the family Acanthaceae. It includes 150 species native to tropical and subtropical regions of sub-Saharan Africa, Madagascar, southern Asia, New Guinea, and Australia.