Common water-plantain (Alisma plantago-aquatica) is an aquatic flowering perennial that can grow in mud or shallow water. Its flowers open in the afternoon. The plant’s Latin name, Alisma plantago-aquatica, comes from a Celtic word for water.
I. Appearance and Characteristics
Alisma plantago-aquatica, also known as European water-plantain, common water-plantain or mad-dog weed, is a perennial flowering aquatic plant.
The species is widespread across most of Europe and Asia from Portugal and Morocco to Japan, Kamchatka and Vietnam. It is also regarded as native in northern and central Africa as far south as Tanzania, and in Australia. It is reportedly naturalized in southern Africa, New Zealand, Alaska, British Columbia, Washington state and Connecticut. Some sources maintain that the species is widespread across North America, but these reports appear to have been based on misidentified specimens. It is found in mud or in fresh waters.
The word alisma is said to be a word of Celtic origin meaning “water”, a reference to the habitat in which it grows. Early botanists named it after the Plantago because of the similarity of their leaves.
Alisma plantago-aquatica is a hairless plant that grows in shallow water, consists of a fibrous root, several basal long stemmed leaves 15–30 centimeters (6–12 inches) long, and a triangular stem up to 1 meter (3+1⁄2 feet) tall. It has branched inflorescence bearing numerous small flowers, 1 cm (1⁄2 in) across, with three round or slightly jagged, white or pale purple petals. The flowers open in the afternoon. There are three blunt green sepals and 6 stamens per flower. The carpels often exist as a flat single whorl. It flowers from June until August. The fruits appear as a ring of seeds inside each flower.
Chemistry
Chemical constituents of Rhizoma Alismatis—rhizomes of Alisma orientale (syn. Alisma var. orientale) as a traditional Chinese medicine—include alisol A 24-acetate and alisol B 23-acetate. The content of these two compounds are significantly different in Rhizoma Alismatis of different areas.
Similar species
Narrow-leaved water plantain Alisma lanceolatum differs only in that the leaf tips are acuminate and shape is narrow lanceolate.
According to some sources, presumed specimens found in North America are actually the similar A. subcordatum and A. trivale.
II. How to Grow and Care
Common water-plantain generally has straightforward care needs, thriving best in wet conditions such as pond margins or bog gardens. Special care should be taken to ensure common water-plantain has consistent moisture and is planted in full sun to partial shade for optimal growth. Due to common water-plantain’s adaptation to aquatic environments, monitoring water levels is crucial to prevent drying out, making its care relatively easy for those familiar with water plants.
Sunlight
Common water-plantain thrives best under full sunlight conditions, which promotes robust growth and optimal health. The intensity of light should be strong, with the plant benefitting from extended daylight hours to ensure vigorous development. While common water-plantain has a good tolerance to partial sunlight, this deviation from its ideal exposure can lead to suboptimal growth, with potential impacts on flowering and overall vitality.
Adaptively, common water-plantain may exhibit physiological adjustments to cope with reduced light conditions. Outdoors, common water-plantain should be positioned where it can receive direct sunlight to reflect its natural habitat preferences. An engaging environment for common water-plantain anticipates its light requirements, ensuring its growth is unimpeded by light-related stress.
Watering
Common water-plantain is a plant that thrives in water-rich environments, often found near ponds and marshes. Its high moisture needs reflect its natural habitat’s conditions. This plant has an exceptional tolerance for wet conditions, making it a great choice for areas with high humidity or rainfall. As for watering frequency, common water-plantain prefers to be watered daily due to its affinity for moist surroundings. Being an aquatic perennial herb, common water-plantain goes dormant during the colder months but requires consistent moisture throughout its active growth period.
Propagation
Native to wetlands, common water-plantain thrives in moist soil and propagates predominantly through division. Gardeners should carefully separate the root clumps while ensuring each new section has adequate roots and shoots for successful transplantation. Tender care during the initial stages post-division supports robust growth. For optimal outcomes, gentle handling of roots and early establishment in similar wet conditions to their natural habitat are recommended for this species.
Transplanting
The prime time to transplant common water-plantain is during mid to late spring, when conditions favor root establishment. Choose a waterlogged or consistently moist location to mimic common water-plantain’s natural habitat. If needed, enrich the site with organic matter prior to transplanting for best results.
III. Uses and Benefits
The rootstocks contain starch and can be boiled or soaked to remove bitterness before eating. Aquatic plants in general should be cooked before consumption to kill parasites.
According to Flora of the U.S.S.R. (1934), “A powder prepared from dried roots is used in popular medicine as a cure for rabies and crushed leaves are used against mammary congestion; fresh leaves are employed in homeopathy. … Since this species is often confused or identified with others of the genus, the reported data may also refer to [A. orientale or A. lanceolatum].” A. is also known as mad-dog weed, as if it could be used to cure rabies, but should not be confused with Scutellaria lateriflora (mad-dog skullcap), which is also sometimes called mad-dog weed.
Alisma orientale is sometimes treated as a variety of this species (A. var. orientale). The rhizomes of A. orientale have been used as a traditional Chinese medicine, ze xie. However, it may have serious side effects or even toxic effects such as hepatotoxicity in patients with chronic hepatitis B.
