Depressed clearweed is a widespread plant found in various environments, from cultivated landscapes to natural settings. Its rapid growth and ground-covering habit make its presence noticeable. Many gardeners and homeowners encounter this plant, which can become a prolific presence in outdoor spaces.
Identifying Depressed Clearweed
Depressed clearweed, scientifically known as Pilea microphylla, has common names like artillery plant and rockweed. It grows low to the ground, typically 3 to 12 inches tall, contributing to its “depressed” moniker. Its tiny, bright green leaves are oval or heart-shaped, giving it a moss-like or fern-like texture.
The stems are fine and branching, forming a dense, mat-like growth. Its flowers are inconspicuous and tiny, usually greenish to white. When disturbed, the male flowers explosively discharge pollen, a mechanism that earned it the nickname “artillery plant.” This plant produces small seeds after flowering, contributing to its spread.
Where Depressed Clearweed Grows
Depressed clearweed thrives in moist, shaded environments, often found in the understory of forests in its native tropical regions of Central and South America and the Caribbean. It shows adaptability to various soil types, preferring well-draining soil with consistent moisture. This plant can establish itself in disturbed sites, including cracks in pavement, garden beds, and lawns.
Its rapid growth rate allows it to spread quickly, forming dense mats across surfaces when conditions are favorable. While it prefers semi-shade or bright shade, it can tolerate some direct sunlight, though excessive exposure can scorch its leaves. This adaptability contributes to its widespread distribution in warm, humid climates, where it can act as an effective ground cover.
Controlling Depressed Clearweed
Managing depressed clearweed involves a combination of methods. Manual removal is effective for smaller infestations. Hand-pulling or hoeing can remove the plant, but it is important to ensure as much of the root system as possible is extracted to prevent regrowth. Thoroughness is important, as tiny seedlings are easily missed.
Cultural practices can help suppress its growth and spread. Improving soil drainage can deter this plant, as it prefers consistently moist, but not waterlogged, conditions. Applying a layer of mulch helps to block light, suppressing germination and growth of new plants. Proper watering practices, avoiding overly wet conditions, also contribute to creating an environment less favorable for depressed clearweed.
For more extensive infestations, chemical options are effective. Pre-emergent herbicides such as oxadiazon, dimethenamid-p, indaziflam, and prodiamine provide control when applied to bare soil to prevent seed germination. Post-emergent herbicides like flumioxazin and oxadiazon control mature plants. Contact herbicides such as pelargonic acid and diquat offer temporary control but often require repeat applications due to potential regrowth. When using chemical controls, carefully follow product label instructions and consider environmental impacts, especially around desirable plants.