This architectural giant is quite at home beside the stream.
Growing to 2m in height and sending up large, leathery, heavily veined and sharply toothed leaves on fleshy, prickly stems, Gunnera manicata (syn. G. x cryptica) is one of the largest hardy herbaceous perennials for cultivation outside in the British Isles. Originating from Chile where it grows in moist grasslands, riparian zones and wetlands. It thrives in humus-rich, permanently wet soils, and is often planted alongside streams and ponds. In early summer it produces erect, closely branched, conical panicles of minute, green or coppery flowers. In its native homeland the young leaf stalks are peeled and eaten in similar fashion to the rhubarb with which we are familiar, and this, and its similarity in appearance to rhubarb plants, has given rise to the common name giant rhubarb. This species is now considered to be a hybrid of G. manicata and G. tinctoria, and has been assigned the name G. x cryptica. It has also been identified as an invasive species, and is banned from sale. Existing plantings can be retained, but measures should be taken to ensure that it this species does not spread beyond the garden in which it is grown, and that if it is removed, material should be destroyed.