Micranthemum glomeratum (widely sold as Pearlweed, and long mislabeled Micranthemum micranthemoides or Hemianthus micranthemoides) is a small-leaved stem plant native to Florida and the wider southeastern United States. Its compact, rounded, slightly arched leaves grow in dense whorls along thin stems, giving it a soft, bushy texture that can be trained as a low carpet or left to grow into a fuller midground stand depending on how it's trimmed. It's genuinely one of the easier and more forgiving stem plants available, and a good stepping stone for anyone who has struggled with fussier true carpeting plants like Monte Carlo.
Care tip: Pearlweed will grow in low-tech, non-CO₂ tanks, but it grows fastest and stays most compact under moderate-to-high light with CO₂ injection. Trim it regularly — left alone it grows upward quickly, and frequent pruning is what keeps it low and dense rather than tall and leggy.
Pearlweed is a fast grower and one of the most adaptable stem plants for a beginner-friendly, low-tech setup — it tolerates a wide range of substrates and water parameters and doesn't demand injected CO₂ to survive, though growth is noticeably faster and more compact with it. Left untrimmed it will grow upward as an ordinary stem plant reaching several inches tall; trimmed hard and planted densely, the same plant forms a soft, low, carpet-like cushion instead. Propagation is simple: cut healthy stem tips and replant them directly in the substrate, where they root quickly and continue the same compact growth.
In the aquascape, Pearlweed works well as a foreground carpet in a nature-style layout, a soft filler between hardscape, or a bushy midground-to-background stand if left to grow taller. Its fine, bright green texture pairs nicely with larger-leaved plants and driftwood, and the dense growth gives shrimp and fry plenty of cover to graze and hide in. Because it tolerates lower-tech conditions better than many true carpet plants, it's a practical choice for tanks that don't run CO₂ but still want a lush, textured foreground.
Pearlweed has a long history of mistaken identity in the hobby: plants sold for decades as Micranthemum micranthemoides were later confirmed by herbarium comparison to actually be Micranthemum glomeratum, a distinct Florida-native species with larger, more upright growth. It's also worth telling apart from Micranthemum tweediei 'Monte Carlo,' a true creeping carpet plant with rounder, denser foliage that is considerably more demanding to keep flat and compact. Pearlweed offers a similar textured, fine-leaved look with a much easier care curve.
| Difficulty | Easy |
| Placement | Foreground to Midground |
| Max Height | 2–6 inches (taller if left untrimmed) |
| Light Level | Moderate to High |
| Temperature | 68–82°F |
| pH | 6.0–7.5 |
| CO2 Needs | Optional (recommended for compact growth) |
| Origin | Florida, USA (North America) |
| Notes | Commonly sold as Pearlweed; long mislabeled as Micranthemum micranthemoides. More forgiving than Monte Carlo and one of the easier stem plants to keep compact with regular trimming. |
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