Chara FAQ

Chara is a complex multicellular green alga — specifically, a charophyte in the class Charophyceae. It is not a true plant, despite looking almost exactly like a small submerged aquatic plant. It lacks roots, leaves, stems, vascular tissue, and flowers — the structures that define true vascular plants. However, charophytes are the closest living relatives of terrestrial plants and share many biochemical features with plants. For lake management purposes, chara is treated similarly to submerged aquatic plants and is managed using algicide treatments (copper-based) rather than herbicides (which target true plants). The distinction matters for choosing the right treatment product.

Chara produces and releases volatile sulfur compounds — primarily organosulfur molecules — that smell strongly of garlic or skunk when the tissue is crushed or when it decomposes. The biological reason for this odor production is not fully understood — it may deter herbivory or play a role in allelopathic (growth-inhibiting) interactions with other organisms. Regardless of cause, the garlic odor is one of chara's most reliably diagnostic features: if a submerged plant-like organism smells like garlic when crushed, it is almost certainly Chara. The closely related Nitella does not produce this odor.

It depends entirely on the ecological context. In clear, nutrient-poor (oligotrophic) lakes, chara is an ecologically valuable keystone organism. Dense chara beds indicate good water quality, stabilize sediment against resuspension, provide food and habitat for waterfowl and invertebrates, and suppress phytoplankton through allelopathic compounds. The loss of chara beds from a clear lake is a warning sign of deteriorating water quality. In this context, chara is definitely "good." In eutrophic, nutrient-enriched ponds and shallow lakes, chara can reach densities that create strong odors, impede recreation, and indicate that nutrients are too high. In this context, the chara itself is a symptom of the problem (excess nutrients) — the chara is not "bad" per se, but managing it while addressing the underlying nutrient problem is reasonable.

For immediate relief in nuisance-level chara situations, copper-based algicide treatments (copper sulfate or chelated copper products) provide effective short-term control. Treatment is most effective during active growth in spring. However, chara will regrow unless the underlying nutrient problem (excess phosphorus and nitrogen from runoff, wildlife waste, etc.) is addressed. Mechanical removal (hand raking and complete removal from the pond) provides temporary aesthetic improvement. Long-term control requires nutrient reduction — eliminating the nutrient inputs that drive excessive growth. Always check with your state DNR for permit requirements before applying any copper treatment. See the full chara control methods guide for complete information.

At normal densities, chara is not harmful to fish. In fact, chara beds provide fish habitat, support invertebrate communities that serve as fish food, and contribute to oxygen production through photosynthesis. In very dense, nuisance-level chara situations, nighttime respiration can reduce dissolved oxygen — the same mechanism as with any other dense aquatic vegetation. Copper-based treatments for chara can harm fish if applied at excessive concentrations, particularly in soft water where copper is more bioavailable. Always follow label directions and calibrate copper treatments based on your water's alkalinity when using copper-based algicides to control chara.

Chara and hydrilla are very different despite superficial similarities. Key distinctions: Chara smells like garlic when crushed (hydrilla has no distinctive odor). Chara feels gritty and calcium-encrusted; hydrilla feels smoother. Chara's whorled structures are multi-branched "branchlets," not simple flat leaf blades like hydrilla. Hydrilla has obvious serrated (toothed) leaf margins; chara's branchlets are not simple toothed blades. Hydrilla has white tubers and roots at the sediment surface; chara has delicate colorless rhizoids. Hydrilla is a federal noxious weed; chara is a native alga with ecological value in most U.S. settings. See the chara identification guide for complete guidance.