1. Guides
  2. Invasive Exotic Plants of North Carolina
  3. Winter Honeysuckle

Winter Honeysuckle

Lonicera fragrantissima

Summary 5

Lonicera fragrantissima is a species of flowering plant in the honeysuckle family known by the common names winter honeysuckle, fragrant honeysuckle, January jasmine, and sweet breath of spring. It is native to China and has been an introduced species to other parts of the world. It was brought to the attention of western gardeners by Scottish plant hunter Robert Fortune, who was plant hunting in China for the Royal Horticultural Society. Fortune introduced Lonicera fragrantissima to...

Ecological threat in the united states 6

Exotic bush honeysuckles can rapidly invade and overtake a site, forming a dense shrub layer that crowds and shades out native plant species. They alter habitats by decreasing light availability, by depleting soil moisture and nutrients, and possibly by releasing toxic chemicals that prevent other plant species from growing in the vicinity. Exotic bush honeysuckles may compete with native bush honeysuckles for pollinators, resulting in reduced seed set for native species. In addition, the fruits of exotic bush honeysuckles, while abundant and rich in carbohydrates, do not offer migrating birds the high-fat, nutrient-rich food sources needed for long flights, that are supplied by native plant species.

Regeneration processes 7

More info for the terms: adventitious, competition, cover, density, epigeal, forbs, frequency, fresh, layering, litter, perfect, root crown, shrub, shrubs, vine

Bush honeysuckles regenerate from seeds, as well as vegetatively following disturbance.

Breeding system: As of this writing (2005) there is very little available information about bush honeysuckle breeding systems. According to Stephens [157] Tatarian honeysuckle flowers are perfect.

Pollination: According to Hauser [68] Morrow's honeysuckle, Tatarian honeysuckle, and Bell's honeysuckle are pollinated by bumblebees. Graenicher states [58] Bell's honeysuckle is pollinated by a variety of bees and perhaps by hummingbirds.

Seed production: Information about seed production is sparse, but it is apparent that some bush honeysuckles are capable of producing substantial numbers of seeds. Barnes [7] indicates Bell's honeysuckle produces consistent annual seed crops. A single "typical" Bell's honeysuckle shrub, about 6.6 feet (2 m) tall, growing in southern Wisconsin, produced 3,554 berries in 1 year. Numbers of seeds/fruit, sampled from several shrubs at this site, averaged 5 to 7, indicating that a "typical" plant may produce >20,000 seeds annually [7].

Estimates of annual fruit production for Amur honeysuckle and European fly honeysuckle in southwestern Ohio ranged from 0 to 1.2 million berries per plant, and approximately 400 million berries ha-1 [80]. According to Welsh and others [191], winter honeysuckle fruits are "seldom formed", although no further explanation was provided.

There is some evidence for shrub age and size as determinants of reproductive ability. According to Sharp and Belcher [150], Amur honeysuckle plants begin flowering in the 3rd or 4th year, after which flowers appear on stems 2 years old and older. Deering and Vankat [33] compared reproductive state with shrub age and height within an Amur honeysuckle population in southwestern Ohio. Established shrubs took 3-8 years to reach reproductive age. At age 3 only 5.7% of individuals were reproductive, while >50% were reproductive by age 5. All shrubs ≥8.2 feet (2.5 m) tall were reproductive, while none <3.3 feet (1 m) tall were reproductive. Bell's honeysuckle shrubs may also produce fruit at as young as 3 years of age [7].

Site characteristics may also affect seed production. Amur honeysuckle flowering and fruiting were significantly (p=0.001 and p=0.03, respectively) correlated with light availability in southern Vermont [139].

Seed dispersal: Several sources indicate bush honeysuckle seeds are dispersed primarily by frugivorous birds [7,80,93,126,186]. Bartuszevige and Gorchov [12] showed that a wide variety of bird species consumed Amur honeysuckle fruit in southwestern Ohio. They also confirmed that American robins dispersed viable Amur honeysuckle seed, usually into woodlot edge and fencerow habitats. White-tailed deer may also consume and disperse viable seeds of Tatarian honeysuckle, Morrow's honeysuckle, Bell's honeysuckle, and Amur honeysuckle [180]. Barnes [7] suggests that "many, if not most" fruits fall near the parent plant. For more information see Importance to Livestock and Wildlife.

Seed banking: It appears the potential for bush honeysuckles to form seed banks is low, but more research is needed to confirm this assertion and to determine interspecific differences. According to Luken and Mattimiro [105], seeds of Amur honeysuckle are "not long-lived in the soil." Hidayati and others [74] concluded that neither winter honeysuckle, Amur honeysuckle, or Morrow's honeysuckle have the potential to form persistent seed banks. However, Stevens and Jorgensen [158] found 12-year-old Tatarian honeysuckle seed to be still viable. They compared germination in seed stored for 12 years with fresh seed. Stored seeds were kept in a dry, open warehouse where temperatures over a 25-year study period ranged from -21.8 to 100.9 °F (-29.9 to 38.3 °C). Seeds from both lots were germinated over a 16-month period in a refrigerator (34 to 38 °F (1.1-3.3°C)). Germination rates were 57% for fresh seed and 31% for 12-year-old seed.

Germination: Bush honeysuckle germination requirements are variable between species.

Winter honeysuckle seeds require warm plus cold stratification prior to breaking dormancy. Although seeds mature in late spring/early summer, they generally will not germinate until late winter/early spring of the following year. A greenhouse study by Hidayati and others [74] indicated that winter honeysuckle seeds germinated while buried under 2 inches (5 cm) of leaf litter or 2.8 inches (7 cm) of soil.

Stratification requirements for Amur honeysuckle seed germination are unclear. According to Luken and Goessling [103], seeds are released in a nondormant condition, and germinate easily in warm, moist conditions. According to Hidayati and others [74], Amur honeysuckle seeds require a period of either warm- or cold stratification. Nevertheless, they are dispersed in fall and may germinate in fall or spring [74,103]. According to Hidayati and others [74], if seeds mature early enough and are subjected to a sufficiently long warm stratification period prior to onset of cold winter temperatures, they may germinate in fall. Late-maturing seeds are cold-stratified over winter, and will germinate in early spring when warm temperatures induce embryo growth.

Light seems to enhance Amur honeysuckle seed germination, but it is not obligatory. In a laboratory experiment, Amur honeysuckle germination was significantly (p<0.01) higher in light (35 µmol m-2 s-1, 14/10 hour light/dark photoperiod) than in dark (light excluded). Nevertheless, after 88 days, mean cumulative germination ranged from 53.7% to 81.3% in light, and from 31.3% to 55.0% in dark [103]. Hidayati and others [74] found that Amur honeysuckle seeds were not inhibited by burial under 2 inches (5 cm) of leaf litter or 2.8 inches (7 cm) of soil in a greenhouse.

Germination may be enhanced when seeds are separated from the fruit pulp. Bartuszevige and Gorchov [12] found that seeds within intact fruit were significantly less viable (44% germination) than either seeds that were separated from pulp by hand (76% germination) or seeds that had passed through the guts of American robins (86% germination), after 12 weeks of favorable laboratory germination conditions.

Morrow's honeysuckle seeds, which are dispersed in summer, require warm stratification only and typically germinate prior to winter [74]. Germination will occur in light or dark. Hidayati and others [74] found that, while Morrow's honeysuckle seeds germinated more readily under light than in dark under laboratory conditions, they were not inhibited by burial under 2 inches (5 cm) of leaf litter or 2.8 inches (7 cm) of soil in a greenhouse. A greenhouse study by Ruesink [139] demonstrated no effect of shading (25% vs. full light) on germination.

Tatarian honeysuckle seed germination is affected by scarification and cold stratification. Krefting and Roe [89] tested the effects of cold stratification, and ingestion and passage by American robins, on Tatarian honeysuckle seed germination. Unstratified seeds recovered from bird droppings germinated more readily (46%) than unstratified controls (24.5%). Stratification (90 days at 41 to 50 °F (5-10 °C) prior to feeding to birds) resulted in substantial improvement in germination, regardless of whether seeds had passed through bird guts (95% for bird ingested seeds, 92% for stratified controls). Although unstratified seed germinated more rapidly if passed through bird guts, this effect was not detected with stratified seed. Apparently avian frugivory has some positive effect on Tatarian honeysuckle seeds with seedcoat dormancy, while simultaneously, cold stratification is effective for breaking internal dormancy.

According to Barnes [7] Bell's honeysuckle germination is epigeal.

Seeds of Tatarian honeysuckle, Morrow's honeysuckle, Bell's honeysuckle, and Amur honeysuckle remain germinable following passage through the guts of white-tailed deer. Vellend [180] measured 76% germination for seeds collected from deer feces, compared with 81% for fresh-collected seeds.

Seedling establishment/growth: Bush honeysuckle seedling establishment appears most successful where litter cover and herbaceous competition are sparse [126,185]. Luken [100] found that after clipping established Amur honeysuckle plants in forested and pasture habitats, Amur honeysuckle seedlings established in forested plots at approximately twice the rate of those in pastures. In pasture plots, grasses and forbs were relatively undisturbed, and probably continued suppression of Amur honeysuckle seedlings. Barnes [7] sampled Bell's honeysuckle seedling density and frequency at 4 sites in southern Wisconsin. The site with the highest seedling frequency (39%) was characterized as a red pine (Pinus resinosa)- and eastern white pine (P. strobus)-dominated overstory and a sparse understory. This site had a primarily pine straw litter layer of variable depth over sandy loam and loamy sand soils. Within this site, Bell's honeysuckle seedlings were found within microsites having little to no litter cover. The site with the greatest seedling density (5,280 seedlings acre-1 ) contained a "very dense" population of mature Bell's honeysuckle shrubs, with near-continuous cover in some places. Observations indicate that at this site, seedlings occurred mainly under mature Bell's honeysuckle, where litter accumulation and herbaceous competition were sparse. Two other sites each had only 1 and 2 Bell's honeysuckle seedlings total. Among reasons provided for the paucity of seedlings at these sites were lack of soil disturbance, a thick layer of leaf litter from the oak overstory, and strong herbaceous and vine competition. A subsample was obtained from another section within 1 of these seedling-poor sites, where a dense population of mature Bell's honeysuckle shrubs had been eradicated during the previous year. Because of eradication treatments, plant litter and herbaceous competition were sparse. Consistent with other observations, substantial numbers of seedlings (26% occurrence, 2,560 seedlings acre-1) were found where litter cover and herbaceous competition were sparse and a seed source had been present [7].

However, the relationship between canopy cover and bush honeysuckle seedling establishment and growth is not straightforward. According to a review by Nyboer [126], bush honeysuckles commonly establish under tall shrubs or trees that serve as perch areas for seed-dispersing birds. As discussed above, canopy shading may also suppress strong herbaceous competition and permit greater bush honeysuckle seedling establishment. However, too much shading may result in reduced seedling establishment and growth [98]. Luken and Goessling [103] studied Amur honeysuckle seedling establishment in forest patches dominated by sugar maple, white ash, and American elm in northern Kentucky. Seedling densities were greatest near the edges of forest patches and declined steadily toward their interior. While they were unable to establish a firm causal link between light levels and seedling densities, light levels and seedling densities were significantly positively correlated (p<0.05; r = 0.88) along transects from forest edge to interior. Ruesink [139] compared Morrow's honeysuckle greenhouse-grown seedlings under full-sun conditions with identical seedlings grown under 25% of full sun. After 50 days, full-sun seedlings were twice as tall and produced 6 times more aboveground biomass. It is likely that in most habitats where seeds are present, such as under the canopy of preexisting bush honeysuckle shrubs or where frugivorous birds find perch sites proximate to fruiting bush honeysuckles, any disturbance that increases light at ground level is likely to release bush honeysuckle seedlings [100].

Deering and Vankat [33] described the age structure and allometric development of a relatively isolated Amur honeysuckle population of recent origin (colonized ~ 1979) in southwestern Ohio. First-year shrubs averaged 1.3 feet (0.4 m) tall and 2 basal stems per shrub. Most individuals were >3.3 feet (1 m) tall by their 3rd year. For the first 4 years of development, numbers of 1-year-old stems averaged 2.2 to 2.6 per shrub. Individual plants averaged 4.3 total stems per plant by age 3. As shrubs reached reproductive age (beginning at 3-8 years), height growth continued, but recruitment of new stems ceased. With time, resource allocation shifted from new basal stem production and height growth in young shrubs to a balance of height growth, radial growth of existing stems, and reproduction in older shrubs [33].

Asexual regeneration: Information on asexual regeneration in bush honeysuckles is generally sparse. Studies cited below are specific to Amur honeysuckle and Bell's honeysuckle. Although it seems likely that these traits are shared by other bush honeysuckles, applicability to other taxa is not confirmed. Since Bell's honeysuckle is a hybrid of Morrow's honeysuckle and Tatarian honeysuckle (see Taxonomy), it is likely that either or both of the parent species share the traits discussed for Bell's honeysuckle below. More information is needed to determine similarities and differences in the biology of asexual regeneration in bush honeysuckles.

Amur honeysuckle will sprout from adventitious buds on the root crown in response to stem damage [105,168]. Repeated cutting throughout the growing season results in continued but diminished sprouting (see Physical/mechanical control) [168]. The sprouting response of Amur honeysuckle to any particular stem damage event does not appear to diminish with stem age [105].

Bell's honeysuckle reproduces asexually by root suckering and layering [7]. Barnes [7] studied root suckering and layering in 4 populations of Bell's honeysuckle in Wisconsin. Between 4 and 7% of shrubs sampled exhibited suckers. Suckers were encountered primarily on small shrubs, and those found on large, mature plants were usually within 2 to 3 feet (60-90 cm) of the root crown. Frequency of layering was estimated by examining all branches of sampled shrubs in contact with the soil surface for evidence of root development. Layering frequency varied between sites, with 1 site having 3% of shrubs showing evidence of layering, 2 sites having 9%, and a 4th site 19%. Layering frequency appeared to be positively related to soil moisture and duration of contact between branch and soil, although there were no supporting data. Barnes [7] also indicated that suckering and layering occurred most frequently on sites where Bell's honeysuckle seedling establishment was poorest.

Sources and Credits

  1. (c) Dave Gunn, some rights reserved (CC BY-NC), https://www.flickr.com/photos/shelley_dave/3360159935/
  2. (c) Nuuuuuuuuuuul, some rights reserved (CC BY), https://www.flickr.com/photos/tonreg/16122314817/
  3. (c) Leonora Enking, some rights reserved (CC BY-SA), https://www.flickr.com/photos/33037982@N04/7014738777/
  4. (c) Steven J. Baskauf, some rights reserved (CC BY), http://bioimages.vanderbilt.edu/baskauf/20757
  5. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Lonicera_fragrantissima
  6. (c) Unknown, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22948680
  7. Public Domain, http://eol.org/data_objects/24636996

More Info

iNat Map

Member of the iNaturalist Network   |   Powered by iNaturalist open source software |   Documentation for developers