Callitriche stagnalis
pond water-starwort
Overview
Callitriche stagnalis is an aquatic annual to short-lived perennial in the family Plantaginaceae, growing as slender submerged stems that end in floating rosettes of small leaves. Submerged leaves are narrow and one- to three-veined; the floating leaves are spoon- to egg-shaped, 0.2–0.8 inch (4–20 mm) long, and crowd into star-like rosettes at the surface. Stems are limp and reach 4–24 inches (10–60 cm). On drying mud the plant forms compact land mats with smaller, fleshier leaves. The flowers are minute, without petals, set singly in the leaf axils and flanked by two small curved bracts; flowering runs from April to October. The near-spherical fruit is about 1.5 mm wide with broadly winged edges, a feature used to tell the water-starworts apart. It grows in shallow still or slow-flowing fresh water and on wet mud of ponds, ditches, streams, and puddles, tolerating a wide range of nutrient levels but not deep shade or strong current.
Native Range
Native to Europe, North Africa, and western Asia, where it is widespread in lowland fresh water. It has been introduced to North America, southern Africa, Australia, and New Zealand, and is recorded as invasive in some of those regions.Suggested Uses
Callitriche stagnalis is used as an oxygenating and cover plant in wildlife ponds and aquaria, where its surface rosettes shelter invertebrates, tadpoles, and small fish. Because it spreads quickly, it is kept to contained or managed water rather than open natural systems where it is not native.How to Identify
Appearance
Size & Dimensions
Height4" - 2'
Width/Spread1' - 3'
Bloom Information
Flowering runs from April to October. The flowers are minute and lack petals, with separate male and female flowers borne in the leaf axils and pollinated by water movement and contact. Small winged fruits develop through summer and autumn and sink or drift to spread the plant.
Detailed Descriptions
Foliage Description
light greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Callitriche stagnalis grows in full sun to part shade in shallow, still or slow-moving fresh water up to about 24 inches (60 cm) deep, and on wet mud at the margins. It adapts to a wide range of water chemistry and tolerates a soil pH from roughly 5.5 to 8.0. In ponds it is planted into substrate or allowed to colonise from floating fragments, and it needs no feeding. Growth is fast in warm, still water, where dense mats can cover the surface and lower oxygen levels at night. Thinning keeps part of the water open and limits this build-up.Pruning
No formal pruning applies. Raking or netting off excess floating growth through summer keeps the surface partly clear, and clearing decaying mats in autumn reduces nutrient release in small ponds.Container Growing
✓ Suitable for container growing
Minimum container size: 1 gallons