Trumpet Honeysuckle (Lonicera sempervirens) of the Honeysuckle (Caprifoliaceae) family is a twining vine with spectacular, red and orange, trumpet-shaped flowers. The genus name honors Adam Lonicer,* a German botanist and herbalist. The specific epithet from the Latin for “always” and “green,” denotes the plant’s evergreen foliage in warmer climates. Occurrence in the U.S. extends from eastern Texas and Oklahoma to Florida and New York, with scattered populations from Iowa to Maine. The precise natural boundaries of its range, particularly to the north, are a bit uncertain––the species is widely cultivated and often jumps the fence. In Arkansas, where it may be deciduous to semi-evergreen, trumpet honeysuckle grows statewide except in portions of the Mississippi Alluvial Plain. In addition, populations in the Ozark Highlands are perhaps introduced. Plants favor a variety of dry to mesic habitats with full to partial sun, such as thickets, successional woodlands, and woodland borders. The species is also known as Coral Honeysuckle.
Trumpet Honeysuckle, with support, can reach 20 feet high. Plants have long, glabrous, vining stems with opposite leaves and lateral, often flowering branches, on which a terminal leaf pair, subtending an inflorescence, is fused together across the leaf bases to form a single shield-like blade. New unbranched stems, growing to 6+ feet long in their first season, emerge reddish to pale green but soon become woody with light gray, smooth bark. In subsequent years, the thin bark becomes fibrous and, especially near the ground, develops long, gray to brown, papery shreds. Stems are round and hollow. Plants often have one or few dominant stems from the rootstock from which a large loose viny mass develops within and above the supporting structure.
New branches from year-old stems produce 2-5 leaf pairs. With sufficient sunlight, these non-twining branches terminate with an inflorescence. Some stem nodes, even those well above ground, develop stubby aerial root-like projections.
As in all of our honeysuckles, the leaves are simple and opposite. Like the stems, they are glabrous. Margins are entire; petioles are short (to ⅓ inch long) on the lower leaves to absent above. Early-season leaves are linear to lanceolate, broadening to elliptic or oblanceolate with maturity. Overall, lower leaves of any particular stem or branch tend to be narrower, more distal leaves broader, from 1-3 inches long and 1-1¾ inches wide. Leaf surfaces, initially a dull reddish green, mature shiny and dark green above and lighter greenish gray beneath. Mature leaves are semi-leathery and may have a waxy coating (glaucous) especially beneath. As noted above, leaves directly below the inflorescence are fused into a single blade, a character the botanists term connate-perfoliate.
The inflorescence, on new growth, consists of whorls of long trumpet-shaped flowers along the terminal portion of the stem. New branches, appearing by mid-February, already show well-developed flower buds. Peak bloom time is April into May with profuse flowering on sunny sites. Each of 1-4 whorls of flowers bear several to 8 sessile tubular flowers, blooming whorl-by-whorl in sequence from lowermost to the stem tip. Flowers orient toward sunlight.
The trumpet-shaped flowers (1½-2 inches long) have a red-orange (coral) exterior and an interior that is initially orange-yellow before also becoming red-orange. The width of the tube increases uniformly from a 1/16 inch base to a flared corolla throat, with 5 short, rounded, spreading lobes. Four lobes are positioned at the upper side of the throat and a single lobe is at the base. All lobes are gently reflexed and lack insect guides. Flowers have 5 stamens (filament + anther) and 1 pistil (ovary + style + stigma). The slender filaments, attached to the lower portion of the corolla tube, are tipped with long yellow anthers, center-balanced at the filaments’ tips. Pollen is bright yellow. Filaments and styles are slightly exserted from the corolla throat. The exposed portion of the filaments is pale reddish; the entire style is white. The globose stigma is positioned slightly beyond the anthers. Nectar glands are at the base of the corolla tube. The pale green, glabrous, sessile, inferior ovary has a water-drop shape with a flattened top where the corolla tube attaches. Corolla, stamens, and style/stigma drop-off cleanly after anthesis, leaving a corona-like scar atop the enlarging, pale green ovary.
Fertilized flowers, with expansion of the ovary, produce spherical berries that become shiny red in mid- to late summer. Tops of the fleshy berries are marked by a small scar which remains from the perianth (calyx and corolla). Berries have up to three ovoid seeds, pressed together. The ⅛+ inch, round-edged, tan to golden seeds have a rounded side and two flattened sides. The entire seed surface is slightly pocked. Fruits not eaten by birds become blackened and shriveled, and may remain on the plant over winter.
When Trumpet Honeysuckle is in flower, it can be a very showy vine in a garden or natural area. It is also showy when in fruit. It provides nectar, pollen and berries to many insects, birds and small mammals, including hummingbirds and swallowtail butterflies. It is easy to establish and can flourish in fairly sunny, well-drained sites. Planted at the base of a small to medium-size deciduous tree, stems can grow naturally into the tree’s canopy with practically no maintenance. For a more tidy appearance during winter months, lower dead stems and branches can be removed. Plants can also be supported by an arbor or trellis, but shaping by removal of living stems may reduce flowering. This honeysuckle is not an aggressive spreader by root or seed. It is easily propagated by layering.
In addition to Trumpet Honeysuckle, three additional vines (2 native and 1 non-native) and three shrubs (all non-native) of the genus Lonicera occur in Arkansas. The vines are: 1) the native Yellow Honeysuckle (L. flava), 2) the native Grape Honeysuckle (L. reticulata), and 3) the non-native, highly invasive Japanese Honeysuckle (L. japonica). The four vines are readily distinguishable during flowering. Japanese Honeysuckle bears lobed leaves at the base near the ground and lacks connate-perfoliate leaf pairs at the stem tips; its tubular white (aging to yellow) flowers are not terminal but occur in pairs in the leaf axils; in addition, it has pubescent leaves and young stems. Grape Honeysuckle, with connate-perfoliate leaf pairs, has tight clusters of whorled, shorter, pale yellow flowers and red berries. Yellow Honeysuckle, too, has connate-perfoliate leaf pairs, but its whorled darker yellow to yellow-orange flowers are shorter and not trumpet-shaped. When Trumpet Honeysuckle occurs in its yellow form (uncommon natural form or cultivars), its longer trumpet-shaped flowers distinguish it from both Yellow Honeysuckle and Grape Honeysuckle. When eradicating Japanese Honeysuckle, special care must be taken to distinguish it from our three native honeysuckle vines if plants are in sterile condition: stems of the alien invasive are pubescent; those of the natives are hairless.
* Also known as Adam Lonitzer and Adamus Lonicerus (1528-1586). His first major work, the Kräuterbuch (the Herbal Book), was published in 1557.
Article and photographs by ANPS member Sid Vogelpohl