If you have hiked down Arlington’s Four Mile Run Trail or the regional W & OD bike path, you have definitely seen Arlington’s most common invasive plant species: Ampelopsis brevipedunculata or porcelainberry. Porcelainberry can grow pretty much anywhere, in both sunny forest edges and partially shaded areas in the forest or along streams. Vines can form dense mats over other vegetation or grow up to 15 ft. in a single growing season. Although porcelainberry is prevalent in Arlington’s parks, it is sometimes difficult to distinguish from another vine species that is native to our area, the grape vine.
It is not recommended to try and identify porcelainberry by the leaves because the leaf shape can differ by location. Identification can be confused further because there are five species of grape that are native to Arlington and all have leaves that are similar to porcelainberry, with three-lobes of varying size and shape.
A great way to identify porcelainberry is to look at the stem. This method of identification can be used any time of year. Both the bark and what is called the pith, the plant tissue in the center of the stem, can help distinguish the species. The bark of porcelainberry has lenticels, while grape bark has straight shaggy bark that peels off in parallel lines.
If you have a small vine, you can do a “Pith Test” where you cut the stem in half to look at the center, or pith. In porcelainberry the stem pith is white, but in native grape it is brown.
Flowers and Fruits
Flowers and fruits can also be used to distinguish between porcelainberry and our native grape, but are only present in late summer and fall. Both the flowers and fruits of porcelainberry grow in in compact, broad clusters. Unlike grape, porcelainberry flowers and fruits grow upright. The berries of porcelainberry are hard and vary in color from white to yellow to lilac to magenta to blue. The flowers of the wild grape in elongated clusters that hang down and the fruits are soft and edible.