One of the most troublesome groups of non-natives plant species is the Honeysuckles. Everyone sees them in their travels and every land manager knows them as highly invasive plants. They all have aromatic red, pink, or white flowers in early spring and later produce a prodigous crop of juicy red, orange, or dark purple berries. Every child used to know the honeysuckle flowers as a source of sweet-tasting "honey" (actually nectar) when bitten at the base of the corolla. Although I hope for their sake they still do this, it's too bad that there is such a ready source of these flowers in the wild.
The non-indigenous honeysuckles can be divided into 2 groups; the twining, climbing ones, represented with us by the Japanese Honeysuckle, Lonicera japonica, and the shrubby ones, actually a confusing group of up to five taxa and numerous potential hybrids (Lonicera maackii, L. morrowii, L. tatarica. L. xylosteum, and L. x bella). There is still a question as to whether or not the Trumpet Honeysuckle, Lonicera sempervirens, is actually native to Connecticut. Assuming for the time being it is, it is not treated here.
Most people don't have trouble recognizing the Japanese Honeysuckle. It climbs over anything and everything, has dark, leathery, evergreen leaves, large white, two-lipped tubular corollas, and dark purple-black berries that ripen in Fall. In contrast, the shrubby non-native honeysuckles are deciduous, with green, non-leathery leaves, smaller flowers, and numerous red or orange berries produced in mid-Summer. The pith of the young twigs is hollow in the non-indigenous shrubs, a good field character to distinguish them from native shrubby honeysuckles such as the Fly Honeysuckle, Lonicera canadensis. They leaf out earlier than most native shrubs and by mid May are usually in full flower. The corollas are smaller than those of the Japanese Honeysuckle and can vary amazingly in color from plant to plant within the same taxon, ranging from a deep red to an almost pure white. The white and pink corollas usually fade to a yellowish white. The shrubby species usually produce red juicy berries although some individuals produce orange, yellow, or even clear berries. The fruits are usually gone from the bushes by September.
All of the non-native honeysuckles are bird dispersed. This is one reason for both their widespread distribution and their success as invaders of all kinds of habitats. Summer resident birds are usually the dispersers as most fruits are gone by early September. Robins, Catbirds, Mockingbirds, and Starlings have been observed feeding on these species but it is likely there are many more.
The non-indigenous honeysuckles occur in almost every habitat type in Connecticut. Almost every woodland near Long Island Sound has Japanese Honeysuckle and probably every abandoned field, vacant lot, power line right-of-way, and forest margin has one or more taxa of the shrubby honeysuckles. They occur, all too frequently, on traprock ridge tops, in pitch pine scrub oak barrens, and in calcareous wetlands. In fact, at one rare plant station in a calcareous fen in northwestern Connecticut, The Nature Conservancy has been running an ambitious program for over 10 years to remove the honeysuckles that are outcompeting the rare native flora at the site.
Not all species of non-native honeysuckles that occur in Connecticut are equally invasive. In fact, one species may only be sporadic and two others appear to be very uncommon. The remaining 3 are widespread, abundant, and invasive. Although it is unlikely in all cases, the distribution record may be an artifact of collections and misidentification in the field. Further fieldwork and collections are needed to clarify these points.
Lonicera japonica Thunb. Japanese Honeysuckle
This species was introduced into North America in 1806 in New York as an attractive ornamental vine (Nuzzo 1996). The earliest Connecticut specimen I have seen is from New Haven, collected in 1858 by Daniel Cady Eaton. The Catalogue of Flowering Plants and Ferns of Connecticut, "Bulletin 14" (Graves et al. 1910), says of this species that it was "occasional or local in most districts, becoming frequent near the coast". It is now widespread in Connecticut with its greatest concentrations in southern counties. This species is easily recognized by its white, long, tubular flowers that fade to a creamy yellowish color; dark purple berries persisting, if not eaten by birds, well into the winter; its evergreen or sometimes semi-evergreen foliage; and its scandent habit. Japanese Honeysuckle climbs over everything, from trees to telephone poles. It produces copious underground stems and is very difficult to control or remove. It used to be widely cultivated but I suspect this is no longer the case.
This complex of 4 species, and a named hybrid consisting of lots of back crosses that make a confident determination nearly impossible, are often lumped together under the generic heading of shrubby honeysuckles. For most conservation and management issues this is probably alright as they appear to be biologically very similar. Interestingly, only 1 species (Lonicera morrowii) and the hybrid (Lonicera x bella) appear to be the real conservation "bad guys" in Connecticut, but we need more information on the distribution and abundance of the remaining 3 species before we can authoritatively make this statement. We must also be watchful of their potentially invasive nature. The complex can be told from the native shrubby honeysuckles by the hollow pith in the young branches and their white, pink or red corollas. All non-native shrubby species of honeysuckle produce red, orange, or yellow (very rarely clear) berries in mid to late summer.
Lonicera maackii (Ruprecht) Maximowiczii Amur Honeysuckle
The Amur Honeysuckle is native to China and Korea. There are differing reports as to when it was introduced into this country; somewhere between 1855 to 1860 (Dirr 1983) and 1896 (Luken 1996). This easily recognized shrubby honeysuckle is distinguished from all of the other introduced honeysuckles by the very short peduncles and by the acuminate leaf tip. I have not seen this in Connecticut and in looking through herbaria in the region, I have only seen one Connecticut specimen collected in the wild. It was collected in Windsor near the Connecticut River in 1978. The specimen was misidentified as Lonicera morrowii. Although this species does not currently appear to be a problem here in Connecticut, it is a serious problem in the Midwest (Luken & Thieret 1997).
Lonicera tataricaL. Tatarian Honeysuckle
This species is native to Central Asia and southern Russia and was introduced in 1752 (Dirr 1983). This honeysuckle is widely used by the nursery and landscaping industries and there are many popular cultivars currently in the trade. Its corollas can range from deep red to pale pink, even white (Dirr 1983). It is commonly planted by bridge abutments and in landscape plantings, probably most often for its deep red flowers, dark green foliage, and red berries. It can be told from other long-peduncled species by its glabrous leaves and twigs. I have not seen this species commonly escape into natural habitats but fear I may have overlooked it. I have seen specimens clearly collected in the wild from only a handful of sites in Connecticut.
Lonicera xylosteumL. European Fly Honeysuckle
There seems to be no record of the year of introduction for this European taxon. Although it has been long cultivated in eastern North America (Dirr 1983). The status of this species as an escape in Connecticut is unclear. It is, perhaps, most commonly confused with the next species and the hybrid and I suspect much confusion has arisen for this reason. I have seen herbarium specimens that appear to be from escaped plants from Groton, Old Lyme, Fairfield, and Westport. None of these are recent specimens. The glandular nature of the ovary seems to be a good field character but you must look at the ovary with a lens. The glands look like the scattered resinous dots on the lower surface of a Gaylussacia baccata leaf and best seen when the honeysuckle is in flower or on young, developing fruits. The obovate leaf shape, is also a good character on the herbarium sheets I examined. I have no familiarity with this species in the wild, although I have misidentified specimens as Lonicera xylosteum on more than one occasion.
Lonicera morrowii A. Gray Morrow’s Honeysuckle
;This Japanese native has been in cultivation in New England since the late 1800s (Luken 1996). This species, along with the hybrid of which this is one of the parents(Lonicera x bella), is the most commonly encountered non-indigenous honeysuckle in the New England flora. It is highly invasive and probably occurs in every town in Connecticut. Characters that separate this species from they hybrid are poorly defined and often I have opted for using what the British birders would call its "jizz", its gestalt. Lonicera morrowii is very hairy and at anthesis the bracteoles at the base of the ovary are usually more than half as long as the ovary. The corollas are usually white, occasionally pink, and fade to a yellowish-white when they are past. Often the plants will be hairy (which points to L. morrowii) but have short bracteoles (which points to L. x bella). I frequently play odds with individuals of this species and the hybrid, going on gut feeling if the characters are variable or inconsistent. This species can exist in dry fields and woodlands as well as in wetlands.
Lonicera x bella Zabel Bella Honeysuckle
This hybrid was first raised from seeds received from Russia before 1889. Lonicera x bella is a fertile hybrid of L. morrowii and L. tatarica. This hybrid, and the proceeding species, appear to cause the most problems as far as invasiveness is concerned. Likewise, they are the most difficult to distinguish from one another (see previous discussion). Like Lonicera morrowii, Lonicera x bella has a wide ecological amplitude and can be found almost anywhere. It too probably occurs in every town in Connecticut. Hybrid individuals can cross with L. morrowii (one of the parents) giving rise to countless potential backcrossed phenotypes. These different phenotypes can range from almost clearly one parent to almost as clearly the other. Determination of material of this and the former taxon must, in many instances, be tentative. Usually individuals of this hybrid have only scattered hairs and the corollas are almost glabrous.
In order to better assess the distribution of all woody, non-native honeysuckles, I need information on three species: Lonicera maackii, Lonicera tartarica, and Lonicera xylosteum. Also, if you see any of the non-native species growing in apparently atypical habitats, I would appreciate hearing from you.
Dirr, M. A. 1983. Manual of Woody Landscape Plants. Stipes Publishing Company, Champaign, IL
Graves, C. B., E. H. Eames, E.H., C. H. Bissell, L. Andrews, E. B. Harger, and C.A. Weatherby. 1910. Catalogue of the Flowering Plants and Ferns of Connecticut growing without cultivation. Bulletin 14, Connecticut Geological and Natural History Survey, Hartford, CT.
Luken, J. O. 1996. Lonicera maackii, L. morrowii, and L. tatarica. Pp. 60-61. in: Randall, J.M. and J. Marinelli, eds. Invasive Plants Weeds of the Global Garden. Handbook 149, Brooklyn Botanic Garden, NY.
Luken, J. O. and J. W. Theiret. 1997. Amur Honeysuckle, its fall from grace. Arnoldia 57:2-12.
Nuzzo, V. 1996. Lonicera japonica. pp. 96. in: Randall, J.M. and J. Marinelli, eds. Invasive Plants Weeds of the Global Garden. Handbook 149, Brooklyn Botanic Garden, NY.
Leslie J. Mehrhoff
George Safford Torrey Herbarium
Box U-43
University of Connecticut
Storrs, CT 06269-3043
(860) 486-1889