Flower:

Erect to ascending pairs of pale yellow flowers arising singly from leaf axils near branch tips, the pair of flowers at the end of a slender, minutely hairy stalk up to 1 inch long. Flowers are ½ to ¾ inch long with a slender tube and 2 lips, the upper lip erect with 4 lobes at the tip, the lower reflexed down, narrower than and about as long as the upper, and both longer than the floral tube. Outer surfaces are hairy, especially the tube. Protruding from the tube are 5 yellow-tipped stamens and a long, slender, green style, hairy towards the base and with a dome-shaped stigma at the tip. The lower half of the floral tube is swollen on one side, and between the flower and cluster stalk is an egg-shaped, green ovary; the ovaries may be separate or joined. Bracts at the base of the ovary are minute or absent altogether,

Leaves and stems:

Leaves are opposite, 1 to 3½ inches long, up to about 1 inch wide, oblong-elliptic and widest at or above the middle, blunt or sometimes rounded at the tip, tapering at the base to a short, minutely hairy stalk. Edges are toothless and hairless.

The upper surface is minutely hairy, the lower is not much paler than the upper and densely covered in soft hairs. Twigs are green to brownish, minutely hairy, and solid with a white pith.

Older bark is brown to gray and often peeling in strips. Branches are straggling and may take root where they touch the ground, forming clonal plants.

Fruit:

Fruit is a bright orangish-red, semi-translucent berry, more or less round, about 1/3 inch in diameter, sometimes the pair joined at the base.

Notes:

Swamp Fly Honeysuckle is a common sight in wetlands in the northern third of the state, especially in peaty soils. In size and general shape it resembles Mountain Fly Honeysuckle (Lonicera villosa), which has dangling trumpet shaped flowers, single blue-black berries with a waxy bloom, and leaves with stiff hairs on both surfaces as well as around the edge, where Swamp Fly Honeysuckle has red berries and leaves with soft hairs that are hairless around the edge. Likewise, Fly Honeysuckle (Lonicera canadensis) has trumpet shaped flowers and leaves hairy only along the edges. While references put Swamp Fly Honeysuckle at a max height of 6 feet (or even more), knee to waist high plants are more the norm in Minnesota.