is a large, leafy vine or shrub, often found in shady, moist areas along canyons. The branched stems are woody, and bear greyish-green leaves at opposite intervals. Leaves have a fine covering of short, soft hairs. The uppermost pair of leaves are fused (a characteristic of this genus), to create an elongated disc right beneath the flower clusters, which are produced in spring at the tips of the branches.
The white or pale yellow flowers have a narrow, tubular, lightly hairy corolla which opens to five lobes, showing bilateral symmetry; one lobe is angled downwards, the other four point upwards. The five stamens have white filaments topped by yellow anthers, fixed at their midpoints. The stamens are exserted, as is the style. Fruits are red-orange berries, forming a ring at the center of the fused leaf.