Images and an introduction to the plant family Gunneraceae
Gunnera plants have two important symbiosis. One is with Mycorrhizal fungae in the soil, which aid in the uptake of phosphates. This is widespread in several groups of plants. For further information, see
Gunnera harbours symbiotic nitrogen-fixing cyanobacteria of the genus Nostoc. The plant produces a clear mucilage which keeps its apex moist and which attract soil caynobacteria, some of which come to live as symbionts within specilized tissues in the plants stem, visible as blueishing green blobs in cross-sectioned stems. This symbiosis means that Gunnera can grow in nitrate poor soils, such as sandy bogs and rocky cliffs.
For further information on the symbiosis, see description and images here, from Stockholm university. Or see the publications below: