Acanthus mollis

Acanthus mollis, commonly known as bear's breeches, sea dock, bearsfoot or oyster plant, is a herbaceous perennial plant with an underground rhizome in the genus Acanthus. It is regarded as an invasive species in some jurisdictions.

This plant is native to the Mediterranean region from Portugal and northwest Africa east to Croatia and it is one of the earliest cultivated species.

Etymology:
The name of the genus derives from the Greek term ἄκανθος, akanthos, the name of the plant in Greek; it was imitated in Corinthian capitals; the word is related to ἄκανθα, akantha meaning "thorn" referring to the thorn-bearing sepals, or any thorny or prickly plant in Greek, while the Latin name of the species, mollis meaning "soft", "smooth", refers to the texture of the leaves.

Description
Acanthus mollis reaches on average 30–80 centimetres (12–31 in) of height, with a maximum of 180 centimetres (71 in), inflorescence included. It has basal clusters of deeply lobed and cut, shiny dark green leaves, soft to the touch, up to 40 centimetres (16 in) long and 25 centimetres (9.8 in) broad, with a long petiole. 

The inflorescence is a cylindrical spike 30–40 centimetres (12–16 in) long and can produce up to 120 flowers. The flowers are tubular, whitish, and lilac or rose in colour. Each flower is up to 5 centimetres (2.0 in) long and it is surrounded by three green or purplish bracts. The central bract is spiny and larger than the other two. The calyx has two lips: the upper is purple on top, rather long and forms a kind of "helmet" on top of the corolla. The corolla is reduced to a white lower lip, trilobed, with purple-pink venation. The four stamens are fused to the corolla and look like tiny brushes. This species flowers in late spring or early summer, from May through August.

Acanthus mollis is entomophilous and it is pollinated only by bees or bumble bees large enough to force their way between the upper sepal and the lower, so that they can reach the nectar at the bottom of the tube. The fruit is an ovoid capsule containing two to four large black seeds. The dispersal of seeds is by the wind (anemochory).

These plants are usually propagated from tubers and tend to form large, localized clumps which can survive for several decades and look statuesque when well-grown, but its suitability as a garden plant is lessened on account of its invasive nature (new plants are produced readily both from seed and portions of root) and its susceptibility to powdery mildew and attacks from snails.