Damasonium polyspermum: complete guide

Overview

Damasonium polyspermum, also known as starfruit, etoile d'eau, or flûteau étoilé, is an elegant aquatic plant from the Alismataceae family that naturally grows in the Mediterranean region. This aquatic plant is distinguished by its star-shaped fruit clusters, which give the plant a characteristic appearance. Unlike many aquatic plants, Damasonium polyspermum grows submerged or in shallow water.

Although not widely cultivated, Damasonium polyspermum is unique and interesting for gardeners wanting to experiment with aquatic plant communities.

Appearance & Bloom

Damasonium polyspermum is a small to medium aquatic plant, typically 10-30 cm tall above the water surface (although much remains underwater). The plant has long, linear leaves growing from the plant base. The flowers are small, white to light pink-tinted blooms that grow above water.

The fruit clusters are the real eye-catchers: stellate (star) shaped, with approximately 8-12 protruding arms, giving the plant its scientific name. The fruits are long-persistent and offer botanical and decorative interest.

Ideal Location

Damasonium polyspermum thrives best in sunny or half-shady water locations. The plant prefers 4-8 hours of sunlight daily, although it can also grow in partial shade. The plant is entirely dependent on water conditions, not dry land.

The plant works well in ponds, water gardens, marshes, or wetland habitats.

Soil/Water

Damasonium polyspermum grows in both acidic and slightly alkaline waters. The plant tolerates muddy, nutrient-rich substrates typical of water habitats. In garden ponds, no special preparation is needed; the plant grows in standard water.

The plant prefers moderately nutrient-rich waters. Moderate nutrient content encourages growth.

Watering

As an aquatic plant, Damasonium polyspermum requires continuous underwater conditions. Plant it directly in pond substrate or in submerged containers. The plant must never drain from water; watering does not apply to this aquatic plant.

The plant can grow at water depths up to approximately 50 cm.

Pruning

Minimal pruning is needed. Remove only damaged or yellowed leaves. Leave fruit clusters in place until they naturally fall off.

Maintenance Calendar

May-June: Planting in pond. Observation of growth. Monitoring for water algae formation. July-August: Observation of bloom and fruit formation. Removal of excess plants if growing excessively. September-October: Continued observation. Fruit clusters visible. No pruning needed. November-April: Plant may go dormant over winter. In very cold areas, protection may be needed.

Winter Hardiness

Damasonium polyspermum is moderately winter-hardy in Mediterranean climates (zones 6-10). In colder climates, the plant may die in very cold winters. In cold regions, the plant can survive in ponds under thick ice via dormant seed.

Companion Planting

Damasonium polyspermum pairs well with other aquatic plants such as water lilies and other aquatic plants. Submerged vegetation helps ecological balance.

Closing Thoughts

Damasonium polyspermum is a unique, decorative aquatic plant for gardeners interested in aquatic ecology. For more plant recommendations and water garden inspiration, visit gardenworld.app for complete garden designs with water elements.