Know Your Natives – Trumpet Honeysuckle

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.

Photo 1: Growing in a shady fencerow, this plant shares its space with other vines. Photo – April 21.

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.

Photo 2: The gray to brown bark is thin and exfoliating, the oldest stems with loose long papery shreds. Supporting tree is Mockernut Hickory (Carya tomentosa). Photo – February 6.
Photo 3: These new stems emerge directly from the bark rather than from lateral buds. They are located 9⅓ feet above ground. New stem and immature leaf growth at left is ¾ inch long. Photo – February 18.
Photo 4: These stems are developing on nodes that had developed axillary stems or branches the previous year (arrow points to dead stub). Photo – February 25.
Photo 5: New stems, whether near ground level or 20 feet into a tree’s canopy, are initially erect and reddish with lanceolate leaves. Many new stems die at the end of their growth year, especially if they do not find support or become over-shaded. Photo – March 20.

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.

Photo 6: These axillary branches are developing from scaly axillary buds on a second-year stem. The more advanced branch on right terminates with flowers (not shown). Photo – February 18.

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.

Photo 7: This mid-winter pubescent flower cluster is 3/16 inch wide. The reddish leaves below it are the subtending, connate-perfoliate leaf pair. Damage to the new green leaves was caused by cold temperatures. Photo – February 18.
Photo 8: Leaves are disposed in opposite, decussate pairs––each pair rotated 90 degrees from the pair above and below it. These early leaves are mostly lanceolate to elliptic and petiolate while the uppermost leaf pair is connate-perfoliate. Photo – April 5.

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.

Photo 9: Inflorescence consists of 1-4 whorls of flowers at the end of branch, including a terminal whorl. Red-orange exterior and initially yellow-orange interior are typical. Note the atypical leaf pair at lower left that is not connate-perfoliate. Photo – April 13.
Photo 10: Lowermost whorls bloom first. As flowers mature, yellowish orange interior becomes the same red-orange as the exterior. While older woody stems (see at lower right) twine tightly about their support, new stems are initially loose. Reproductive branches do not twine. Photo – April 23.
Photo 11: The loose viny upper-mass of this plant is mostly from a single dominant stem (same plant in Photo 2). Support tree is Mockernut Hickory. Photo – April 13.
Photo 12: The globose stigma is positioned slightly beyond the elongate center-balanced anthers. Note the inferior ovaries (below the corolla tubes) and corona-like rims, remains of the calyx, atop the ovaries. Squares = ¼ inch. Photo – May 18.
Photo 13: Upper section of tube removed to expose pubescent interior. Stamens are attached below to the corolla tube, not, like the tube itself, to the summit of the ovary. Stigma partially hidden at left. Photo – May 18.

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.

Photo 14: Tops of the red spherical berries bear remains of the calyx and a scar where the corolla tube detached. As indicated by the blackened branch to the left, terminal portion or entire branch dies after fruit maturity. Photo – August 26.
Photo 15: Dried fruits with up to 3 viable seeds may remain on branches over winter. The slightly pocked ovoid seeds have a tan to golden color. Squares = ¼ inch. Photo – April 19.

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

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