Hydrilla vs Milfoil: Key Identification Differences

Visual Identification: Hydrilla vs. Milfoil

When determining "what does hydrilla look like" compared to Eurasian watermilfoil (Myriophyllum spicatum), the primary distinction lies in their leaf structures. While both are invasive submerged aquatic plants that form dense mats, a quick visual inspection of a single leaf node is usually enough to tell them apart.

Misidentifying hydrilla as milfoil (or vice versa) can lead to ineffective management strategies, as the chemical and biological control methods for these two distinct species vary significantly.

Leaf Structure Comparison

The most reliable way to differentiate these plants is to examine a single leaf removed from the stem.

Stem and Growth Habit

Both plants are capable of forming incredibly dense, impenetrable mats at the water's surface, shading out native vegetation and impeding recreation.

• Stems: Eurasian milfoil stems are often reddish or brownish and become leafless toward the base. Hydrilla stems are typically green, profusely branched, and retain leaves further down.
• Flowers: Milfoil produces tiny, reddish flowers on emergent spikes that stick out above the water surface. Hydrilla's female flowers are tiny, translucent-to-white, and float on the surface attached by a long thread.
• Root Systems: Only hydrilla produces subterranean tubers (small, potato-like structures). Finding tubers in the sediment is a definitive confirmation of hydrilla.