Native vs Invasive Honeysuckle: The Hollow-Pith Test

Cut one stem and look at the center. Invasive shrub honeysuckles have a hollow pith. Native fly honeysuckle and native bush honeysuckle have solid pith. That one cut settles most bush honeysuckle questions. A vine on a fence is a different plant, and it needs a different check.

The 60-second pith test

Use a stem about the thickness of a pencil. Cut it cleanly and look at the cut face, not the bark.

Penn State Extension describes the invasive shrub honeysuckles as a complex of several species: Amur honeysuckle (Lonicera maackii), Morrow’s honeysuckle (L. morrowii), Tatarian honeysuckle (L. tatarica), Belle honeysuckle (L. × bella), and Standish’s honeysuckle (L. standishii). They hybridize, and the source says they are not different enough in identification or treatment to separate them for control work.

The same source names native fly honeysuckle (Lonicera canadensis) and native bush honeysuckle (Diervilla lonicera) as the look-alikes with solid pith. It also warns that native snowberry (Symphoricarpos) has a hollow pith, so the pith test alone is not enough there. Check the flowers and fruit. Native viburnums and dogwoods also have solid piths, and their leaves and stems differ.

The vine case: Japanese honeysuckle

Japanese honeysuckle (Lonicera japonica) is not a shrub. It is a trailing or climbing vine, and it is invasive.

The University of Maryland Extension says it arrived in the United States in 1806 on Long Island, New York, and was planted for erosion control, ornament, and wildlife browse. It climbs by twining around objects. Native honeysuckles, the same source notes, spread using tendrils, adhesive disks, or aerial roots rather than twining.

Older Japanese honeysuckle stems are woody and hollow, with brown bark that peels off in shreds. Leaves are opposite, about 3 inches long, egg-shaped, hairy, and smooth-edged. Flowers appear from April to July. They are white, tinged with purple or pink, and turn yellowish with age. The fruit is a shiny black berry that ripens from September to November.

So the pith test works on the shrub complex. For the vine, use the twining habit, the paired opposite leaves, and the white-to-yellow tubular flowers.

When each one flowers and fruits

The invasive shrub honeysuckles leaf out early and hold foliage late compared with most native woody plants. Penn State Extension notes that this gives a longer treatment window, but it also makes the shrubs easy to spot in early spring.

Why the difference matters

Invasive shrub honeysuckles are spread by abundant fruit eaten by birds and small mammals. The berries are available from midsummer through winter. Penn State Extension notes that the fruit has far lower nutritional value than native plants, and that eating this “junk food” has been linked to harm in some wildlife.

Japanese honeysuckle spreads by seed, rhizomes, and runners. UConn’s invasive plant program says it can quickly cover small trees, stunt or kill them, reduce light and soil moisture, and cause trees to topple under the weight of vines. The Maryland source adds that it can girdle shrubs and saplings.

Japanese honeysuckle, Amur honeysuckle, Morrow’s honeysuckle, Tatarian honeysuckle, and Belle honeysuckle are on Connecticut’s invasive plant list, which marks them as prohibited by statute. Rules vary by state. Check your own state’s list before you plan disposal or planting.

What to plant instead

The safest swap is a native that grows in the same light and soil, not another honeysuckle from a garden center.

Ranges differ across the country, so confirm which of these is native where you live before planting. Your state extension office or a local native plant society can give you a county-level answer. If you are in Virginia, start with the Virginia state page.

If you decide to remove it

Do not cut shrub honeysuckle and walk away. Penn State Extension says mechanical control alone is not enough because plants readily resprout from stumps. Mowing or cutting must be followed by an herbicide treatment to the cut stump or to the regrowth.

For Japanese honeysuckle, UConn’s guidance is hand-pulling for small patches, with all roots and shoots removed from the site. Mowing is not effective and can stimulate denser growth. The Maryland source says fall herbicide applications are best for Japanese honeysuckle, and that glyphosate and triclopyr are effective active ingredients.

Penn State Extension names glyphosate alone for shrub honeysuckle where it is the only invasive target, and water-based triclopyr to improve results where other invasive plants are present.

This page does not give mixing rates or a herbicide prescription. Read and follow the product label; the label is the law. Confirm the product is labeled for your site, your state, and the plant you are treating. If the stand is large, near water, or next to plants you want to keep, get site-specific advice before you start.

What to do next

• Confirm the plant with the pith cut and the flower or fruit, not the leaf alone.
• If it is a native, leave it and plant more of it.
• If it is invasive, check your state rules, then plan a multi-year control program rather than a single cut.
• If you are replanting, browse the prevention guides before you buy.
• Browse the identification guides or the plant profiles for the next species.
• For another invasive shrub that forms dense thickets, see multiflora rose and its fringed-stipule test.

The decision is simple: a solid white pith means keep looking for a native; a hollow pith on a shrub honeysuckle means you have an invasive plant to manage.