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.