Lonicera is a moderately large genus of ca. 200 species, mostly native to the northern hemisphere. Two are native in Belgium as well, Lonicera periclymenum L. and L. xylosteum L.
About half of the species of the genus are cultivated for ornament. Their fruits (berries) are much eaten by birds and therefore easily dispersed. In addition to the taxa treated in detail in this account several others possibly also occur as escapes from cultivation. Lonicera maackii (Rupr.) Maxim. was recently found in the Netherlands (de Boer 1999). Clement & Foster (1994) cite several additional species. A cultivar of native Lonicera periclymenum with corollas that are pinkish-purplish outside is increasingly found in the wild, for instance in coastal scrub in Koksijde since several years (pers. obs.). In 2011 it was also observed near Verviers (see: http://waarnemingen.be/waarneming/view/55955784). Such plants possibly belong with cv 'Belgica'.
Lonicera xylosteum is a rare and local native species. It is naturally confined to calcareous soils, especially in the area between rivers Meuse and Sambre in Wallonia. However, outside its native distribution range it is increasingly found as an escape from cultivation in many, widely scattered locations, primarily in Flanders (disused railway yards, seadunes, abandoned cemeteries,…) (see also Duvigneaud 1988).
1. Climber, stems twining === 2
1. Erect or prostrate shrub === 7
2. Flowers in pairs === Lonicera japonica
2. Flowers in whorls === 3
3. Upper pair of leaves free, not united into a disc === 4
3. Upper pair of leaves fused === 5
4. Leaves lanceolate, acuminate at apex and slightly cordate at base, deciduous to semi-evergreen. Berry black. Inflorescence short-stalked (stalk at most 15 mm long). Young shoots hirsute-hairy === L. acuminata
4. Leaves oblong, more or less rounded at apex and tapered to base, deciduous. Berry bright red. Inflorescence long-stalked (stalk 25-45 mm long). Young shoots glabrous or minutely pubescent (native) === L. periclymenum
5. Evergreen. Corolla red with five equal, short lobes, glabrous outside === L. sempervirens
5. Deciduous. Corolla distinctly 2-lipped, cream or yellowish, sometimes tinged purplish, often glandular pubescent outside === 6
6. Bracteoles minute or absent === L. caprifolium
6. Bracteoles ca. ½ as long as ovary, obscuring its base === L. xitalica
7. Evergreen small shrub, rarely exceeding 100 cm (sometimes taller in cultivation). Corolla greenish yellow, minute (5-8 mm). Leaves glabrous, at most 30 mm long. Fruit violet === 8
7. Deciduous (or rarely semi-evergreen) shrub, usually much taller. Corolla cream or reddish, more than 8 mm long. Leaves larger, usually hairy (at least on the veins beneath when young). Fruit red === 9
8. Most leaves almost at right angles to the stem (90°), ca. 12-14 mm long. Leaf apex more or less rounded (leaves pointed egg-shaped). Adaxial leaf surface with median vein usually indistinct === L. nitida
8. Most leaves angled forwards at ca. 45°, ca. 20-26 mm long. Leaf apex attenuate (leaves narrowly elliptic). Adaxial leaf surface with median vein often raised, distinct === L. pileata
9. Stem solid. Flowers appearing before leaves === L. xpurpusii
9. Stem hollow. Leaves appearing before flowers === 10
10. Corolla reddish or whitish, (10-) 15-30 mm long. Leaves and twigs almost glabrous === L. tatarica
10. Corolla cream, 8-15 (-25) mm long. Leaves and twigs densely and softly pubescent === 11
11. Upper corolla lip split to base in 5 equal lobes. Ovary usually glabrous. Leaves and twigs more or less persistently hairy === L. morrowii
11. Upper corolla lip divided for at most ½ its length. Ovary glandular. Leaves and twigs eventually often more or less glabrescent === 12
12. Leaves 60-120 mm long, acuminate at apex. Upper corolla lip divided for ca. ½ its length. Corolla 15-20 (-25) mm long === L. chrysantha
12. Leaves 30-60 mm long, more or less acute at apex. Upper corolla lip divided for at most ¼ of its length. Corolla 8-12 mm long (native) === L. xylosteum
Bradshaw D. (1995) Know your honeysuckles. The Garden 120: 406-411.
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
De Boer E. (1999) Een wonderlijke vondst van een gekweekte kamperfoelie, Lonicera maackii (Rupr.) Max., op Gewone vlier. Gorteria 25: 28-29.
De Koning J., Van den Broek J.W., Van de Laar H.J. & Fortgens G. (2000) Nederlandse dendrologie (13e druk). H. Veenman & zonen, Ede: 585 p.
Duvigneaud J. (1988) La réserve naturelle domaniale de Poilvache à Houx (Yvoir). Mise en évidence de sa vocation didactique. Nat. Mosana 41(4): 113-136.
Li D.Z. (2000) Lonicera. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 436-452.
Rehder A. (1903) Synopsis of the genus Lonicera. Annual Rep. Missouri Bot. Gard. 14: 27-232.
Roloff A. & Bärtels A. (2006) Flora der Gehölze (2e Auflage). Ulmer, Stuttgart: 844 p.
Stace C. (1997) New flora of the British Isles, 2nd ed.: XXVII + 1130 p. Cambridge University Press.
Van de Laar H.J. (1988) Lonicera. Dendroflora 25: 37-54.
Whitehouse C. (2012) Trial of climbing Lonicera (subgenus Lonicera). The Plantsman N.S. 11(1): 10-15.
Wright D. (1983) Climbing honeysuckles. The Plantsman 4(4): 236-252.
Yang Q., Landrein S., Osborne J. & Borosova R. (2011) Caprifoliaceae. In: Flora of China Editorial Committee (ed.), Flora of China, vol. 19. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 616-641.