Botanist's Lens: Exotic Liana invading ecosystems with Arbuscular Mycorrhiza Fungi to its aid.
Lianas (woody creeping plants) can easily add an artistic touch to any landscape, unless one of them is an aggressive invasive. Most Lianas hang onto tall canopy trees for structural support throughout their lifespan. Although not detrimental to the host tree itself, they can dominate the canopy layer and compete for nutrients, light and space.
One particular Liana that caught my attention this week was Celastrus orbiculatus (Oriental bittersweet) hanging onto a wild Cherry tree along the periphery of London Town. The striking yellow and orange berries hanging delicately on the twisted stems, paint quite an intricate picture. Unfortunately, this Liana is bad news for the Eastern ecosystems.
Oriental Bittersweet is a very aggressive vine with a dominant habit that is invading in the Eastern ecosystem since the mid-1800s. The native species Celastrus scandens (American Bittersweet) is actually in decline in forests. "In the Northeast, Oriental bittersweet appears to be displacing the native climbing bittersweet, Celastrus scandens, through competition and hybridization." (https://www.invasive.org/eastern/midatlantic/ceor.html).
Correct identification is crucial, since the two vines have close resemblance. Here is a good link to understand the difference: https://www.fs.usda.gov/In…/FSE_DOCUMENTS/fsbdev3_017307.pdf.
What I find most intriguing about Oriental Bittersweet is that it is probably very successful as an invasive, because it shows symbiotic relationship with Arbuscular mycorrhizal fungi (AM fungi). "A determining factor regarding Oriental bittersweet's ability to outcompete native plant species is its ability to form mutualistic associations with mycorrhizal fungi, specifically arbuscular mycorrhizal. Oriental bittersweet growth is highly dependent on the absorption of phosphorus. In a recent study, growth was found to be greater when arbuscular mycorrhizal fungi were present in soil with low phosphorus concentrations. The results from this study show the importance of symbiotic relationships in allowing Oriental bittersweet to effectively uptake nutrients from its surroundings" (https://en.wikipedia.org/wiki/Celastrus_orbiculatus)
Oriental Bittersweet also has the advantage of having a thicker and longer stem than the native species. Plants with an extremely aggressive and invasive habit can be detrimental to any ecosystem. Oriental Bittersweet is found on roadsides, forests and even areas with poor nutrient quality. It has been observed to cover half an acre in just 10 years! Of course they have AM fungi to the rescue that helps it grow faster.
Oriental Bittersweet fruits are quit attractive and very popular in Floriculture for making wreaths and seasonal arrangements. But by using Oriental Bittersweet for wreaths, it sets a greater risk for the seeds to be spread by their best dispersal agents, birds! When handling the vines with fruits, it is best to use them for indoor arrangements with caution for seed dispersal, and bagging it to discard it when finished using for decorations. But once identified correctly, this Liana must be eradicated by best management practices for preservation of natural ecosystems.