Fly honeysuckle (Lonicera xylosteum, L. 1753)

Identity

Fly honeysuckle (Lonicera xylosteum L., 1753) is a deciduous shrub in the Caprifoliaceae family, also called European fly honeysuckle or dwarf honeysuckle. Its French names include chèvrefeuille des haies, camérisier des haies, and chèvrefeuille à balais. The epithet xylosteum combines Greek xylon (wood) and osteon (bone), referring to yellowish wood so hard that it was once fashioned into pegs, spindles, and pipe stems. ^{1 9}

Usually 1–3 m (3–10 ft) tall, occasionally reaching 4 m (13 ft) in favorable conditions, the shrub forms a dense bush with four-angled branches that turn from gray to reddish brown. Its young stems are hollow, distinguishing it from Lonicera nigra, which has solid pith, and from the introduced Lonicera tatarica, with hairless leaves. ^{2 3}

Recognition

Opposite, oval to elliptical leaves measure 3–7 cm (1.2–2.8 in) long. Dense hairs cover their undersides, while only scattered hairs occur above. This difference can be felt before it is readily seen. ⁹

Spring into early summer brings pairs of tubular, two-lipped flowers in the leaf axils, corresponding to April–June in the Northern Hemisphere conditions described. Each flower is about 1–1.5 cm (0.4–0.6 in) long. White when newly open, they yellow with age, allowing several generations of flowers to be distinguished on the same branch at once. ^{2 9}

The round berries are bright, glossy red, 6–8 mm (0.2–0.3 in) across, and joined in pairs at their bases. A rarer form described as xanthocarpa produces yellow berries instead of red ones. ^{3 2}

Taxonomy and names

Within Caprifoliaceae, POWO/WCVP accepts the name Lonicera xylosteum L., 1753. Its synonymy includes several forms and varieties once described separately, including Lonicera xylosteum var. xanthocarpa DC., for yellow-fruited plants, and Lonicera xylosteum f. glabrescens Zabel, for plants with less hairy leaves. ¹

Older scientific names now placed in synonymy include Caprifolium xylosteum and Chamaecerasus xylosteum. ⁹

French names such as chèvrefeuille des haies, chèvrefeuille à balais, and camérisier des haies partly overlap with names for other Lonicera species, making the Latin binomial the safest reference. The French word camérisier also refers to Lonicera caerulea, a species with edible blue berries. Sharing a name therefore says nothing about whether the berries of Lonicera xylosteum are safe to eat. ⁸

Habitat and range

Across Europe, apart from the Mediterranean fringe and the far northeast, the native range reaches east to central Siberia (Altai) and northeastern Turkey, according to POWO/WCVP. ¹ Within this range, the shrub grows in countryside hedges, open woodland edges, and calcareous scrub, from lowland sites into upland country. ⁹

Ornamental introductions to North America have naturalized in several northeastern and Midwestern states. Missouri Botanical Garden considers Lonicera xylosteum potentially invasive and discourages planting it in gardens in that region. That recommendation concerns a particular introduced range, rather than its native European habitats. ³

Life cycle, ecology and cultivation

Flies carry out most pollination, explaining the name fly honeysuckle. ³ Birds later feed on the red berries and disperse the seeds. Czech Wikipedia nevertheless also lists birds among the animals susceptible to the fruit’s toxicity. ⁹

In cultivation, the shrub tolerates chalk, clay, loam, and sand and grows in full sun or partial shade. Hardiness to −20 °C (−4 °F) means established plants generally need no winter protection after their first year where winter lows remain within that tolerance. ² Fly honeysuckle can be propagated from softwood cuttings in summer or hardwood cuttings in fall. Light pruning immediately after flowering preserves the following year’s flower buds. These seasonal operations follow local growth rather than a universal calendar. ²

Uses and risks

Once planted in informal countryside hedges, fly honeysuckle has fallen out of favor with nurseries. Vigorous growth, suckering, and limited ornamental interest after flowering explain why it is seldom recommended for clipped hedges today: it requires disproportionately more maintenance than other hedge species. ⁹ It nevertheless retains value in polluted urban settings, where tolerance of air pollution and salt spray can justify keeping it. ⁹

The berries are poisonous if ingested. Czech Wikipedia suggests saponins as the probable cause of their toxicity and reports chest pain after five berries, as well as poisoning after about thirty, with severe manifestations including vomiting, abdominal pain, diarrhea, fever, and cold sweats. ⁹ The FDA bibliographic index lists this species in its record of R. Jaspersen-Schib’s 1984 article on poisonous plants in autumn. ⁷ Czech Wikipedia also reports an experiment in which a handful of berries caused fatal paralysis in rabbits; it lists toxicity to horses, hares, and several rodents without assigning them that same dose or outcome. ⁹

Cultivars and look-alikes

Unlike related species such as Lonicera caerulea, Lonicera xylosteum has no horticultural cultivar that is widely marketed today. Its main notable variation is the yellow-fruited form, listed in WCVP synonymy as xanthocarpa. It occurs in the wild and is rarely offered by nurseries. ¹

Hollow branches distinguish Lonicera xylosteum from Lonicera nigra, with black berries and solid pith. Hairless leaves point instead to the introduced Lonicera tatarica. Fruit color alone presents a third trap: guelder rose (Viburnum opulus), from a different family, carries similar red berries but has lobed leaves, quite unlike the oval foliage of fly honeysuckle. ⁸

Main sources

• Plants of the World Online / Kew, Lonicera xylosteum L.
• Royal Horticultural Society, Lonicera xylosteum (fly honeysuckle)
• Missouri Botanical Garden, Lonicera xylosteum
• GBIF, Lonicera xylosteum L. species page
• Integrated Taxonomic Information System (ITIS), Lonicera xylosteum L.
• USDA PLANTS Database, Lonicera xylosteum L. (LOXY)
• FDA Poisonous Plant Database, bibliographic record of Jaspersen-Schib (1984), Lonicera xylosteum (archived)
• Wikipedia FR, Chèvrefeuille à balais (Lonicera xylosteum)
• Wikipedia CS, Zimolez obecný (Lonicera xylosteum)