Aquatic PlantsBeginner🌗 Medium light

Pearl weed

Hemianthus glomeratus · also called Pearlweed, Hemianthus micranthemoides (trade name), Micranthemum glomeratum, Baby tears (loosely)

🐾 Pet-safe

Generally non-toxic to cats and dogs.

A versatile small-leaved stem plant with tiny bright-green leaves in whorls, usable as a delicate background bush or, when grown horizontally under strong light, a low carpet. The plant in the trade is Hemianthus glomeratus, long mislabeled as 'Hemianthus/Micranthemum micranthemoides.'

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Quick facts

Category	Aquatic Plants
Family	Linderniaceae
Native origin	Southeastern United States
Care difficulty	Beginner
Light	Medium light
Pet toxicity	Pet-safe

Light

Medium to high light. Under medium light it grows as a loose upright stem plant; under high light (40+ PAR) it stays compact and can be trimmed into a low foreground carpet. More light yields denser, more horizontal growth.

Water

Temperature 18-28 C (64-82 F), pH 5.0-7.5, soft to moderately hard water (GH 2-12). Adaptable. Benefits from water-column dosing of a complete fertilizer, especially when grown as a demanding carpet.

Soil & potting

A rooted stem plant (not an epiphyte). For carpeting use, plant small portions into nutrient-rich aquasoil; root tabs help in inert substrates. Grows well drawing from the water column too. Plant or scatter small clumps into the substrate to establish a mat.

Environment — humidity, temperature, placement

CO2 is not required for upright growth but is strongly recommended to achieve a tight, low carpet. Use in the foreground (carpet), midground, or as a background bush. Tolerates a range of flow. Grows emersed and submersed.

Propagation

Spreads readily by side shoots and creeping stems. Propagate by trimming and replanting cuttings; for carpeting, repeatedly trim the top growth to encourage horizontal spreading. Fast and easy to fill in.

Toxicity detail

Non-toxic and safe with fish and shrimp; popular in shrimp tanks. Taxonomic note: the true Micranthemum micranthemoides (Nuttall's mudflower, native to the eastern US) is considered extinct in the wild, and the aquarium plant is actually Hemianthus glomeratus. Not a major aquarium-trade invasive, but do not release into local waterways.

Growth stages

How this plant changes through its life — each stage often has its own care, diet and space needs.

Photo coming soon

Spore / recruit

Aquatic plants and macroalgae establish from spores, seeds, or drifting fragments that settle and attach to substrate or rock. Many freshwater aquarium plants and marine macroalgae also spread readily from a detached piece that takes root or holdfast.

Photo coming soon

Young growth

Young growth puts out its first blades, fronds, or leaves and anchors with roots or a holdfast. Submersed plants may look different from their emersed form, and growth speeds up as the plant adapts to the water's light and nutrients.

Photo coming soon

Mature

A mature aquatic plant or macroalga reaches its full size and characteristic shape, forming the dense growth, runners, or fronds typical of the species. Established plants spread to fill space and can be divided or trimmed to propagate.

Sources

Micranthemum micranthemoides - Wikipedia (encyclopedia)
How to grow Hemianthus glomeratus / Pearlweed - 2Hr Aquarist (care guide)