Introduction to the Menyanthaceae Family

Welcome to the Menyanthaceae, probably my favorite aquatic plant family. I say “probably” because my son says all plants are my favorite! The Menyanthaceae is a small but globally important family that plays a crucial role in wetland ecosystem structure and function all across the globe.

As a child growing up in the mountains of coastal British Columbia, Canada, I first encountered this family. I would see bogbean (Menyanthes trifoliata) growing in the shallow mountain lakes, covered with damselflies and dragonflies, with tiny little fish and frogs swimming beneath them. Even then I recognized it as its own little ecosystem. I also loved deer cabbage (Nephrophyllidium crista-galli) immediately when I discovered it as a teen—I thought its shiny green kidney-shaped leaves with crenate (rounded-toothed) edges were so beautiful, and I did not even get a chance to see its gorgeous frilly white flowers until several years later!

Join me as we explore this globally critical but too often over-looked plant family.

Common Botanical Description

If you’re new to plant morphology, this easy guide is a perfect beginner’s description for learning to identify the Menyanthaceae family, with no need to know any scientific jargon. This is great news for newcomers to plant morphology because there are a LOT of different words used, sometimes even different words used to describe the same feature! So here at least, we’ll keep it simple.

Below this section is additional information on uses and wildlife values. Then we have morphology photos to help you identify the features of the Menyanthaceae family, followed by pictures of individual species of the Menyanthaceae family that I have found so far in North America.

For researchers or those wanting to learn a more in-depth version, refer to the Scientific Botanical Description below the images for highly detailed scientific descriptions and genus-level distribution data throughout the Americas, from Arctic Canada to the tip of South America.

Leaves and Stems of the Menyanthaceae:

The Menyanthaceae are all strictly aquatic or wetland perennial herbs that are rooted and use rhizomes or stolons to remain alive through droughts and winter. They have simple to compound leaves with 3 leaflets (trifoliate). Leaves are arranged alternately on the stem, although some have basal aggregations of leaves and some aquatic forms have floating leaves.

Flowers of the Menyanthaceae:

The Menyanthaceae mostly have bisexual flowers that contain both male (stamens) and female (ovary, style, and stigma) parts on the same flower, although some Nymphoides have separate male and female flowers on separate plants (dioecious). Flowers are small to medium in size with 5 petals that are usually fringed or crested and often have a bearded inner surface. They also have five sepals, which may be free or fused at the base.

Reproductive Features of the Menyanthaceae:

The Menyanthaceae always have 5 fertile stamens that alternate with the corolla lobes. The ovary has 2 chambers that are fused and it is attached above the point of petal attachment (superior) or may be partially inferior. There is a short style divided into 2 stigma lobes.

Fruits of the Menyanthaceae:

Fruits of the Menyanthaceae are always dry capsules that split apart at maturity, but occasionally the fruit is thickened and almost succulent-like, so it is sometimes described as a berry even though it is not.

Uses of the Menyanthaceae Family

Menyanthaceae species are of economic importance as ornamental water garden plants, with Nymphoides being most commonly traded and Liparophyllum and Ornduffia also grown on a smaller scale in Australia for wetland restoration. I always encourage planting native aquatic species to prevent the naturalization and invasiveness of non-native water plants in North America and globally.

On the ethnobotanical side, Menyanthes trifoliata has a long history of use in Europe, Asia, and North American traditional medicines. It has been used as a bitter tonic to stimulate appetite and bile and treat scurvy, rheumatism, and fevers. Modern research (Kowalczyk et al. 2019) shows it does have antioxidant and anti-inflammatory properties.

Ecosystem and Wildlife Values of the Menyanthaceae

Here is where the Menyantheaceae has the biggest impact globally since they play vital roles in the structure and function of freshwater wetland ecosystems all across the globe. They add crucial habitat structure and diversity in wetlands, allowing biodiversity to flourish, and they help filter suspended solids in the water.

For instance, Menyanthes and Nymphoides have extensive creeping underwater rhizomes and stolons that stabilize soft sediments, while the dense mats of Menyanthes trifoliata often form the structural foundation of floating sphagnum mats, which create habitat for other plants, invertebrates, and more. Floating-leaved species like Nymphoides also create important cover and habitat in shallow waters for small fish, frogs, salamanders, and more, protecting them from avian predators.

Then, the fringed, showy, nectar-rich, textured flowers of Menyanthes and Nymphoides are crucial nectar sources for specialized and generalist native bees, hoverflies, and butterflies.

Morphology of Menyanthaceae in North America

Some Species of Menyanthaceae Found in North America

Menyanthes trifoliata—Bogbean

Menyanthes trifoliata is a widespread member of the Menyanthaceae family. It is a rhizomatous emergent aquatic (it grows in standing water from rhizomes), often found in shallow ponds and lakes, peat bogs, and fens, often forming floating mats that create habitats for countless other plants, invertebrates, and amphibians. It has leaves divided into three leaflets (trifoliate) and produces white flowers with a deeply 5-lobed corolla with inner petals that are very frilly. It is native across the temperate and subarctic Northern Hemisphere. In the Americas, it is widespread in Canada, Alaska, and the northern USA. I found this patch in the shallow edge waters of Carlson Lake on the Sunshine Coast of British Columbia, Canada.

Nephrophyllidium crista-galli—Deer Cabbage

Nephrophyllidium crista-galli, or deer cabbage, is another Menyanthaceae member found in wet, mountainous areas like wet meadows, bogs, and subalpine and alpine seeps. It has a much narrower native range, found only in the North Pacific rim from Alaska south through British Columbia, Canada, to Oregon, USA, and also in Japan. It has simple kidney-shaped (reniform) leaves that are thick and glossy and have distinctive round teeth (crenate or scalloped) on their margins, growing from long petioles. Flowers are white or cream with the characteristic fringe of the family but with a prominent fleshy ridge running along the center of each petal lobe.

Scientific Botanical Description of the Menyanthaceae Family

Habit & Leaf Form

The Menyanthaceae family consists of aquatic or wetland rhizomatous or stoloniferous perennial herbs that are typically not succulent, have alternate leaves, and often exhibit a basal aggregation of leaves, except for aquatics with floating leaves. Leaves are arranged alternately in a spiral pattern and have petioles with sheathing or ± winged margins, but no stipules are present. Plants are rooted, typically hydrophytes, but some members can survive in the muck without true standing water.

Leaves are simple to trifoliate leaves that are sometimes peltate and typically have broad leaf bases. When simple, the lamina is pinnately or palmately veined and cross-venulate. Leaves have hydathodes to secrete excess water, and anomocytic stomata are usually present on both surfaces, except the floating leaves of Nymphoides, where they are confined to the adaxial surface.

Flowers

The Menyanthaceae plants are hermaphrodites with bisexual flowers whose pollination is entomophilous, except for a few species of Nymphoides, which are dioecious. Dimorphic heterostyly occurs in all genera except Liparophyllum.

Inflorescences are variable. They can be scapiflorous or not, and they can be solitary or aggregated in fascicles, many-flowered cymes, panicles, racemes, or involucrate heads, with or without involucral bracts.

Flowers are small to medium, actinomorphic, usually 5-merous, and tetracyclic. A free hypanthium is absent, and an intrastaminal hypogynous disk is present. The perianth has a distinct calyx and corolla with 10 parts in 2 isomerous whorls.

The calyx has 5 parts in 1 whorl, which are fused at the base or nearly free. The corolla has 5 parts in 1 whorl, and it may be appendiculate with interstaminal scales or not. The corolla is connate with a floral tube, valvate or induplicate valvate, and actinomorphic. Petals are often fringed or crested and typically have conspicuously fimbriate-bearded adaxial surfaces that help distinguish the family from the Gentianaceae. They also have five sepals, which may be nearly free or basally connate.

Androecium

The Menyanthaceae androecium consists of 5 members, although it is occasionally interpreted as having 10 members if the scales that sometimes alternate with the stamens are interpreted as staminodes rather than as the more common interpretation of being outgrowths of the corolla. Androecial members are free of one another and adnate at the base, midway, or in the throat of the corolla tube.

The androecium has five stamens that are exclusively fertile, isomerous with the perianth, and oppositisepalous with filaments alternating with the corolla lobes. Anthers are sagittate, versatile, dehiscing via longitudinal slits, introrse, and tetrasporangiate.

Gynoecium

The gynoecium is 2-carpelled, the pistil is 1-celled, and the ovary is 1-locular. The gynoecium is syncarpous and superior or partly inferior. There is 1 style that is terminal and shortly bifid, with 2 stigmas that are wet type and papillate. Placentation is parietal (two placentas), usually with 10-50 ovules per cavity that are horizontal, anatropous, unitegmic, and tenuinucellate.  

Fruits

Fruits in the Menyanthaceae family are non-fleshy, dehiscent loculicidal capsules, but they may be septicidal or valvular capsules. Although occasionally the pericarp is thickened and was occasionally described as berries in older flora, they do not produce berries. Fruits contain 4–100 seeds that are endospermic and oily and may be winged or wingless.

Taxonomy of the Menyanthaceae Family

The Manyanthaceae currently has 58 accepted species in 6 genera. It is part of the Asterales order of the core dicots. While they are further divided into 2 tribes, here we will treat them at the family level because there are so few genera.

Genera of the Menyanthaceae Family:

Liparophyllum (8), Menyanthes (1), Nephrophyllidium (1), Nymphoides (52), Ornduffia (7), Villarsia (3).

Key Differences From Similar Families

The Menyanthaceae is not often mistaken for other families except the Gentianaceae. It was even formerly placed in the Gentianales order under the widely used Cronquist system because it shared morphological traits with the Gentianaceae, including fused corollas, parietal placentation (a unilocular ovary), and the presence of bitter iridoids. It has even been treated as a subfamily within the Gentianaceae in older floras. However, DNA evidence showed that it was much closer related to the Asteraceae and Campanulaceae families instead.

The two can be differentiated by the opposite leaves of the Gentiancaeae and the strictly aquatic habitat and alternate leaves of the Menyanthaceae. The Gentianaceae also have smooth inner petals, while the Menyanthaceae petals are distinctly fuzzy or fringed. Chemically, the iridoids of Menyanthaceae differ chemically from those of Gentianaceae.

Distribution of the Menyanthaceae Family

The Menyanthaceae family is mostly a temperate family, though it is cosmopolitan. In the Americas, it is found from northern Canada south into Central and South America, but it does not reach the Southern Cone.

There is also an interesting distribution with the genera themselves, with Menyanthes and Nephrophyllidium growing only in the Northern Hemisphere, while Liparophyllum, Ornduffia, and Villarsia occur only in the Southern Hemisphere. Nymphoides, on the other hand, has a cosmopolitan distribution.

Distribution of the Menyanthaceae in the Americas

Canadian Menyanthaceae Genera:

Menyanthes monospecific circumboreal genus native to all of Canada, inc. the Arctic (and Greenland); Nephrophyllidium monospecific genus native to BC, also AK, Japan; Nymphoides 2 spp. cosmopolitan genus native to ON, QC, NB, NS, and NL (exc. Labrador) and introduced to BC.   

USA Menyanthaceae Genera:

Menyanthes monospecific circumboreal genus native to much of the USA, including AK, but excluding TX, OK, KS, AR, LA, MS, AL, GA, SC, FL, TN, and KY, and extirpated in DE; Nephrophyllidium monospecific native to WA, OR, and AK, also in BC, Canada and Japan; Nymphoides 6 spp. cosmopolitan genus native to WA, CA, AZ, TX, OK, MO, AR, LA, MS, AL, GA, FL, SC, NC, VA, TN, IN, OH, PA, MD, DE, NY, CT, RI, MA, VT, NH, and ME and intro to KY and IL.

Mexico Menyanthaceae Genera:

Nymphoides 2 spp. cosmopolitan genus native to much of Mexico, exc. NW Mexico. 

Neotropical Menyanthaceae Genera:

Nymphoides 4 spp. cosmopolitan genus native to CAM, the Greater Antilles, Leeward Is., Trinidad-Tobago, and tropical SAM S to N Argentina (exc. N Chile), and it has been introduced in the Venezuelan Antilles.

Patagonia Menyanthaceae Genera:

Absent

Additional Information and References

• Visit Lyrae’s Dictionary of Botanical Terms to learn the terminology of botanists. Note that if you hover over most of the words in the articles, you can also get definitions from them there.
• Willis, Lyrae (Unpublished). Plant Families of North America. This is where all of the family descriptions come from. Below should be most of my references for this, along with my own personal observations throughout North America.
• Canadensys: Acadia University, Université de Montréal Biodiversity Centre, University of Toronto Mississauga, University of British Columbia. http://data.canadensys.net/explorer (accessed 2020 – current)
• FNA 1993+. Flora of North America. https://floranorthamerica.org/Main_Page. Accessed 2022-current.
• GBIF.org (2020+), GBIF Home Page. Available from: https://www.gbif.org
• iNaturalist.org 2020+. https://www.inaturalist.org/. Accessed 2020-current.
• Kowalczyk T, Sitarek P, Skała E, Rijo P, Andrade JM, Synowiec E, Szemraj J, Krajewska U, Śliwiński T. An Evaluation of the DNA-Protective Effects of Extracts from Menyanthes trifoliata L. Plants Derived from In Vitro Culture Associated with Redox Balance and Other Biological Activities. Oxid Med Cell Longev. 2019 Oct 16;2019:9165784. doi: 10.1155/2019/9165784. PMID: 31737178; PMCID: PMC6816005.
• Naturalista: CONABIO http://www.naturalista.mx (Accessed 2020–2022).
• Neotropikey: Milliken, W., Klitgård, B., & Baracat, A. eds. 2009+. Neotropikey: Interactive key and information resources for flowering plants of the Neotropics. www.kew.org/neotropikey.com (accessed 2020 – current).
• Patagonia Wildflowers: Wildflower Identification Site. https://patagoniawildflowers.org/ Accessed throughout the fall of 2020.
• POWO 2019+. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: http://www.plantsoftheworldonline.org/. Accessed 2020-current.
• Stevens, P. F. 2001+. Angiosperm Phylogeny Website. Version 14, July 2017 [more or less continuously updated since]. http://www.mobot.org/MOBOT/research/APweb/
• USDA, NRCS. 2020+. The PLANTS Database (http://plants.usda.gov, 2 June 2020). National Plant Data Team, Greensboro, NC, USA; Accessed 2020-present.
• Watson, L., and Dallwitz, M.J. (1992). The Families of Flowering Plants: descriptions, illustrations, identification, and information retrieval. Version: 2nd May 2020. delta-intkey.com. Accessed spring through fall of 2020.
• WFO (2022+): World Flora Online. Published on the Internet: http://www.worldfloraonline.org. Accessed Spring 2022 – current

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Copyright Information

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You can cite this site as Willis, Lyrae (2020+). Lyrae’s Nature Blog – Plant Families of North America. https://lyraenatureblog.com/