Lonicera involucrata aka Californian Honeysuckle

Lonicera involucrata is a deciduous shrub known as twinberry. It belongs to the honeysuckle family, Caprifoliaceae. Its native range runs from Alaska and Canada south to Mexico. It also reaches the Lake States and Quebec. Wild plants grow beside streams, in swamps, and in woods. Some sites have limestone soils or open conifer cover. This is an upright shrub with a spreading, bushy form. Garden heights range from about 6–13 feet [1.8–4 metres]. Plants can reach 16 feet [4.9 metres] in the wild. Mature spread can reach 13 feet [4 metres].

The leaves grow in opposite pairs and fall in winter. They are green, simple, and oval to oblong. Their tips taper to points, and their edges lack teeth. Fine hairs often line the edges and cover the undersides. Young stems have a square cross section. Slender twigs start yellow-green, then turn reddish brown. Older bark ranges from yellow-gray to gray-brown and peels in strips. The leaves and paired fruit help distinguish this shrub.

Small, tubular yellow flowers grow in pairs. Some flowers show a red tint. Bloom falls in June and July in many gardens. In warm-winter areas, it can begin as early as March. Two green bracts sit around each flower pair. These turn red as the season moves on. Paired berries follow, ripening to dark purple or shiny black. The flowers and fruit both add garden interest. The shrub attracts birds, butterflies, and hummingbirds. It also provides wildlife food and cover.

Grow twinberry in full sun or partial shade. It can also cope with deeper shade. Moist, rich loam with good drainage suits it best. It accepts clay, sand, chalk, and a broad pH range. It grows well in wet sites and adapts to drier ones. Sources list USDA zones 4–10 and UK hardiness H6. Care needs are low, with no major pest problems reported. Aphids, thrips, and glasshouse whitefly can still occur. Dry soil can lead to powdery mildew. Seeds and cuttings offer ways to raise new plants.

Twinberry serves as a hedge, screen, or erosion-control shrub. Self-sown plants can spread into colonies over time. Reports of fruit edibility conflict, so do not eat the berries. Plants For A Future records raw or dried fruit use. It also notes that some fruit tastes very bitter. The RHS warns against eating the fruit, including for pets. Recorded traditional uses include bark and leaf remedies. Fruit has also supplied dye and a hair treatment. These reports do not establish that home remedies are safe.