The frequent confusion between bindweed and morning glory is understandable, as both plants are twining vines that produce trumpet-shaped flowers and share a similar growth habit. However, these plants are distinctly different. Knowing the difference is crucial because one is a desired ornamental vine while the other is a globally recognized, highly persistent agricultural weed.
Shared Family, Different Genera
Both the plants commonly known as bindweed and morning glory belong to the same botanical family, Convolvulaceae, named the morning glory family. This shared family lineage explains why they possess similar foundational characteristics, such as the winding stems and the funnel-shaped flowers. The name Convolvulaceae is derived from the Latin word convolvere, meaning “to wind.”
Despite this familial bond, the plants are separated into different genera, signifying a major divergence in their genetic makeup and growth habits. Ornamental morning glories are primarily classified under the genus Ipomoea, which includes hundreds of species. Bindweed is typically found in the genera Convolvulus or Calystegia, with Field Bindweed (Convolvulus arvensis) being the most well-known weedy species. This taxonomic separation reflects the significant differences in their physiology and practical impact on the landscape.
Visual Cues for Telling Them Apart
The most straightforward way to distinguish between the two is by closely examining the leaves and flowers. Morning glory leaves are characteristically large and heart-shaped, often with three distinct lobes. In contrast, the leaves of Field Bindweed (Convolvulus arvensis) are smaller, typically shaped like an arrowhead, with pointed tips and two small lobes at the base.
Flower size provides another clear visual distinction. Ornamental morning glory blooms are noticeably larger, often measuring two to four inches in diameter, and they display a wide range of vibrant colors. Bindweed flowers are significantly smaller, usually only one to two inches across, and their coloration is often limited to pure white or pale pink.
The presence of small leaf-like structures called bracts near the flower is a specific marker. Field Bindweed has two small bracts located about an inch below the flower. Hedge Bindweed (Calystegia sepium) has larger bracts that completely enclose the calyx, the green cup-like structure at the base of the flower.
The Practical Difference Noxious Weed vs Ornamental Vine
The practical difference between the two plants centers on their respective root systems. Most cultivated morning glories are annuals, completing their life cycle in a single season and spreading primarily through seeds, making them relatively easy to manage. Even perennial morning glory species have a less aggressive root system that is easier to remove by hand.
Bindweed is a highly aggressive perennial weed whose persistence stems from its extraordinary underground network. Field Bindweed develops an extensive root system composed of deep taproots and lateral rhizomes. These roots can penetrate the soil to depths of 10 to 15 feet, storing vast energy reserves that allow the plant to regenerate year after year.
This deep rooting makes manual removal nearly impossible, as the plant can sprout a new vine from a root fragment left five feet underground. Cultivation or tilling, which might manage other weeds, actually exacerbates the bindweed problem by breaking the brittle rhizomes into numerous pieces, each capable of forming a new plant. This regenerative capability, combined with seeds that can remain viable in the soil for up to 50 years, cements bindweed’s reputation as one of the most problematic weeds globally.