Round-Leaved Sundew Drosera rotundifolia – Native Plant of the Week

Introduction

I have always been a sucker for all things weird and unique, especially when it comes to native plants. Drosera rotundifolia or the Round-Leaved Sundew was the very first carnivorous plant I saw in the wild and I was immediately in love. To this day it is still one of my favorites. It is a tiny little plant with round leaves covered in sticky glands it uses to capture its prey, any insect small enough to get trapped in its sticky glands including mosquitoes, flies, butterflies, moths, etc. It kills its prey in about 15 minutes but then it slowly digests the insects using digestive enzymes secreted from the sticky glands. The digestion process can take 1 – 3 weeks during which it obtains nitrogen and other nutrients from their little corpses. This may sound a bit on the morbid side but I find it fascinating.

This adaptation allows Round-Leaved Sundew to thrive in the poor nutrient conditions of bogs, marshes, fens and other marginal wetland habitats like lake shores and even floating logs in lakes. In these conditions, it thrives, in part because few other plants can so it has minimal competition. This also puts them at threat due to the loss of our wetlands. While the populations are still secure they are becoming seriously threatened locally in some areas due to habitat loss. They are also challenging to cultivate due to the need for a long period of winter dormancy to develop their winter buds known as hibernacula. Hibernacula allow cold-adapted aquatic plants to survive harsh winter conditions. Cultivars are now available that do not require this, but then they are cultivars and not the wild type.

Description of Round-Leaved Sundew Drosera rotundifolia

Stem & Leaves

Drosera rotundifolia is part of the Droseraceae family in the Caryophyllales order of flowering dicots. It is a very small plant, usually around 3 – 10 cm tall not including its inflorescence which can grow to a maximum of 35 cm tall. It forms a basal rosette of leaves 4 – 10 (2 – 15) cm in diameter. In winter it goes dormant forming hibernaculum, small buds of tightly coiled leaves that can survive the harsh winters.

Leaves are erect or prostrate on petioles 1.5 – 5 cm in length. It has stipules 4 – 6 mm long that are adnate to their petioles along their entire length. Petioles are glandular-pilose (covered with sticky glandular hairs).

Leaves are suborbicular (almost round) and are 0.4 – 1 cm long by 0.5–1.2 cm wide. They are wider than they are long and they are always shorter than their petioles. Leaves, like the petioles, are glandular-pilose covered with sticky glands used to capture and digest their prey.

Flowers & Fruits

The flowers appear from June to September in one-sided inflorescences of 2 – 15 (-25) flowers on scapes that grow up to 35 cm tall but are usually 10 – 20 cm tall. Individual flowers are 4 – 7 mm in diameter with 5 white to pink spatulate petals 5 – 6 mm long by 3 mm wide. Its oblong sepals are basally connate and 4 – 5 mm long by 1.5 – 2 mm wide.

Its fruit is a 5 mm capsule with light brown 1 – 1.5 mm fusiform seeds with longitudinal striations.

Similar Species Frequently Confused With

Drosera rotundifolia is such a unique plant it would be impossible to mistake it for any other genus. However, there are multiple species of Drosera in North America that it could be confused with. Some hybrids are forming in North America with intermediate morphological features, none of them have the distinct round (suborbicular) leaves of Drosera rotundifolia. The different species of Drosera in North America can be differentiated as follows:

• Drosera anglica – the Greater Sundew – looks similar and grows in similar habitats but more in western North America, in the east it is more restricted to Canada and the most northern US states. This one is easily differentiated however by its long narrow linear–spatulate leaves that are never round (suborbicular) like the Round-Leaved Sundew. See the two images below with Drosera rotundifolia on the left and Drosera anglica on the right.
• Drosera capillaris – the Pink Sundew – looks similar and grows in similar habitats but is found at low elevations only and is found in the southeastern part of the US, southern Mexico, Caribbean and northern South America. It can be easily differentiated by its very pink flowers and its appressed rosette of leaves that grow very close to the ground and are never erect.
• Drosera brevifolia – the Red Sundew has a similar range as Drosera capillaris and can be differentiated by its small size, seldom more than 3 cm across, and its wedge-shaped red leaves.

Distribution of Round-Leaved Sundew Drosera rotundifolia

Round-Leaved Sundew has a circumboreal native distribution, found throughout the entire Northern Hemisphere south to the subtropics.

In Canada Drosera rotundifolia is native in all provinces and all northern territories.

In the USA, Round-Leaved Sundew is native to Alaska, Washington, Oregon, California, Idaho, Montana, Colorado, North Dakota, Minnesota, Iowa, Wisconsin, Illinois, Indiana, Michigan, Ohio, Kentucky, Tennessee, Mississippi, Alabama, Georgia, South Carolina, North Carolina, Virginia, Washington DC, Maryland, Delaware, West Virginia, Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire, Maine. It is absent from the interior deserts and plains.

Round-Leaved Sundew is not found in Mexico or anywhere south of the southern USA.

Habitat & Growing Conditions of Round-Leaved Sundew

Drosera rotundifolia is a carnivorous plant adapted to the low nitrogen conditions of bogs, fens, and marshes. It is also found in wet stands of black spruce, silty and boggy shorelines and wet sands. Round-Leaved Sundew can even be found on floating logs in lakes. It is found from 0 – 3000 m elevations and is often quite common in mountain bogs, fens and swamps.

Drosera rotundifolia prefers wet and acidic soil types found in wetlands and will not tolerate drought. It prefers open sun but will grow in part shade. It will not grow in full shade. Round-Leaved Sundew is not found outside of these habitat types. As a result, it is becoming threatened in some places where too many wetlands have been drained or otherwise lost.

Growing Round-Leaved Sundew in Your Garden

Growing species native to your area is a great addition to your garden. Once established they require little to no maintenance of any kind. They already grow in your area without water or fertilizer, so they will easily grow in your yard if you live in their range. They also provide important wildlife and biodiversity values.

You can purchase plants from your local nursery specializing in native species and grow them in your wetland garden. If you do not live in a cold enough climate you may need to purchase a cultivar that does not require winter dormancy. Plant it in sunny locations in moist poorly-drained soils with an acidic pH. They will grow particularly well with mosses and on the edges of ponds. If starting from seed start plants in peat pellets and when they are large enough transplant the peat pot into your chosen spot.

If you want to grow this plant but do not have a wetland garden already please do your research on wetland plants. You will need a low spot with poor drainage and if you do not have one you will need to artificially create one. I will not get into that here because that is a whole separate article.

Wildlife Values of Round-Leaved Sundew

Bog-dwelling ants are opportunistic scavengers that obtain a significant portion of their diet by scavenging prey stuck in the sticky leaves of Drosera rotundifolia. Moose have been seen eating Round-Leaved Sundew in Alaska.

Status of Drosera rotundifolia

Round-Leaved Sundew, with its circumboreal distribution, is considered Globally Secure, G5 and IUCN Least Concern.

In Canada Round-Leaved Sundew is Locally Secure S5 in BC, Alberta, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland including Labrador. It is Apparently Secure S4 in Saskatchewan and Manitoba. In the Yukon Territories it is considered Vulnerable. It has no status rank (unassessed) in Nunavut and the Northwest Territories.

In the USA Drosera rotundifolia is not considered Locally Secure in any state. It is Apparently Secure S4 in Rhode Island and Virginia. Round-Leaved Sundew is Vulnerable S3 in Montana, Indiana, Ohio, West Virginia, Maryland and North Carolina. It is Imperiled S2 in Colorado, Illinois, Delaware and Georgia. It is Critically Imperiled S1 in North Dakota, Illinois, Tennessee and Alabama. In all the other states it is found it has no status rank (unassessed).

Round-Leaved Sundew is not found in Mexico.

Traditional or Other Uses of Round-Leaved Sundew

Drosera rotundifolia Medicinal Uses

In North America various First Nations peoples, particularly the Kwakiutl used the plant as a dermatological aid for warts, bunions, and corns. The Kwakiutl also used it as a love potion.

In Europe the glistening secretions on the leaves used to be used in anti-aging potions because it was believed to be a source of youth and virility. It has also been used as an antibiotic to treat tuberculosis and other respiratory infections. Sometimes it was also used as a love potion because of its ability to lure and trap helpless insects to its sticky leaves.

Drosera rotundifolia has been studied in recent times and shows potential as an anti-inflammatory and antispasmodic.

Round-Leaved Sundew as an Ornamental or Tools

In Sweden the leaves of Round-Leaved Sundew were used to curdle milk and make cheese.

Early settlers sometimes extracted a red fluid from sundews to use as ink.

Ethical Wildcrafting of Drosera rotundifolia

Check the status in your state or province before harvesting since it is imperiled, threatened or vulnerable in several states and provinces. See above section on Status. Alternatively, purchase plants from your local nursery and grow them in your wetland garden. If you do not live in a cold enough climate you may need to purchase the cultivar that does not require winter dormancy.

If you are harvesting Drosera rotundifolia from the wild as always use the 1 in 20 rule of Ethical Wildcrafting. Pick one in every 20 leaves or plants you see, but only if the population is large and stable. Do not harvest from marginal wetlands.

Wildcrafting and Processing

Picked leaves or plants can be placed in a bowl or a jar. Do not use paper bags as you will lose all the sticky juices to the paper bags.

Medicinally Round-Leaved Sundew is generally used fresh. Store it in a glass jar in the fridge until needed. Generally speaking fresh herbs in the fridge do not last more than 1 – 2 weeks.

You can also plant the entire plant in your garden in peat-rich moist soil substrates and grow the plants to extend their medicinal benefits and enjoy the plant themselves. If you live in a cold enough climate and provide the right conditions it could return year after year. Do not feed the plants, and keep them very moist.

References and Resources

Canadensys Plant Search https://data.canadensys.net/vascan/search

Dictionary of Botanical Terms – by Lyrae’s Nature Blog https://lyraenatureblog.com/blog/dictionary-of-botanical-terms/

Eflora Plants of North America http://www.efloras.org/browse.aspx?flora_id=1

Fire Effects Information System on Drosera rotundifolia https://www.fs.fed.us/database/feis/plants/forb/drorot/all.html

iNaturalist Plant Search https://www.inaturalist.org/home

IUCN https://www.iucnredlist.org/

Native American Ethnobotany http://naeb.brit.org/

Natureserve Explorer https://explorer.natureserve.org/Search

USDA Plants Database https://plants.sc.egov.usda.gov/home

Wikipedia on Drosera rotundifolia https://en.wikipedia.org/wiki/Drosera_rotundifolia

Willis, Lyrae (2022).  Plant Families of North America.  Not yet published. 

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