I’d lived in San Diego for ten years before I heard that this plant is acanthus. It’s everywhere and it’s famous but I didn’t recognize it. Acanthus leaves show up in classical and classically-inspired architecture.
2) The dark Corinthian capitals are the remains of Windsor plantation house in Port Gibson, Mississippi. The acanthus leaves are the bottom two rows of ornaments just below the volutes or scrolls.
3) The light portico is at Stanton Hall in Natchez. The capitals on the giant columns are not classical but prominently feature acanthus. Interestingly, the pilasters or squared off columns against the house are standard Corinthian as are the columns by the front door.
4/5) The next two photos are of the 1892 Mills Building in San Francisco by Burnham and Root. The leaves on this building are more lively and star shaped. In addition to being on the columns and pilasters they decorate the middle band of the arch over the front door.
6) Lastly, the carved wooden mold was for casting plaster leaves for interior decoration. I love this immediate connection to classical architecture growing in my own back yard.