Sundew (Drosera) General Information

        Sundews are one of the most intriguing genera of all carnivorous plants. The sticky traps they employ are instantly eye catching with great glistening appeal. Drosera Rotundifolia was used for the basis of Charles Darwin's work in Insectivorous Plants, the scientific work that first provided direct evidence of plants being carnivorous. In Darwin's own words, “I care more about Drosera than the origin of all the species in the world.” It's incredibly easy to see how he became fascinated with these beautiful plants.

Etymology

        Drosera is formed from the Greek root of drosos, or “dewdrops”. Sundew comes from the latin “ros solis” meaning dews of the sun. Going back to the Principia Botanica published in 1787, states that the genus derives it's name from “small drops of liquor-like dew, hanging from its fringed leaves, and continuing in the hottest part of the day, exposed to sun.” These descriptions speak to Drosera's habit of always having dew present when in healthy growing conditions.

Botanical History

        The history of Drosera is strange, because the plant has been for different forms of regional medicine for many years. Even today, Drosera is still used as an herbal treatment in some areas of the world for Whooping Cough. How many years has Drosera been in use by human cultures to be precise, needs a more diligent researcher than I to discover. Over my years of researching Drosera, I have come across a few references of how older cultures viewed the plants. In more superstitious times, Sundews were viewed as magical for their ability to maintain dew in the intense sunlight of midday. As more rational scientific thoughts arose, the dew was viewed as a defense mechanism. It wasn't until Charles Darwin definitively proved the carnivorous action of the genus that the dew's true purpose was revealed.

Habitat & Behavior

        Drosera occur across an incredibly vast global range and in many diverse environments. Through all of these habitats, a few common threads emerge. Drosera occur usually acidic soils that are poor in nutrients, with plentiful access to a water source or high humidity, and have very little overhead competition for light. There are species that defy these conventions, but for the most part they're found as bog dwelling plants. It's important to note that most the commonly sold species are bog growing, making it difficult for somebody to know that other species require different conditions without research. To further illustrate this point, lets look at some more specific examples.

        Drosera Rotundifolia occurs across a large diverse range in the Northern Hemisphere. Typical, this species is found near temperate bogs or fens, growing closer or amongst sphagnum moss, and is usually always wet throughout the year. Drosera Ordensis occurs in Northern Australia, grows in sand, rarely occurs near moss, and experiences intense heat and dry conditions for 8-9 months out of the year. The extreme differences in environment make it hard to suggest general cultivation techniques that will work for all species. In my personal experience, most cultivation issues with Drosera occur from not respecting the conditions that species prefers in nature. If you're having a hard time with one particular Drosera species and not others, it's definitely time to do some research to find out what you need you change for success.

Lifecycle

        Sundews start their lives as incredibly tiny seeds, usually black in color. Depending on the species, they may require some form of stratification for germination. Generally speaking, spring is the time when the plants will sprout. There are exceptions to this rule, though germination usually occurs before the Spring “like” season for those species. After germination, Drosera will have carnivorous leaves appear as their second set of leaves. At this small size, only incredibly tiny prey will be captured by the plants. This first year tends to be the hardest for most sundews, as their size makes them incredibly susceptible to pest, disease, or environmental changes. Where a more mature specimen could handle drying out during a drought in Summer, the small seedlings are far less likely to survive. This leads to a natural thinning of populations, where clumps or clusters of Drosera can be found in the wild. These clumps are surrounded usually by sporadic appearances of other specimens that are much less fortunate to have germinated in the more prime real estate.

The first year of growth ends differently for the various Drosera sections. Tuberous Sundews will die back to small underground tubers, similar to carrots. Petiolaris will die to a small fuzzy rosette, designed to capture any moisture they can from the air during their dry season. Temperate Sundews will form hibernaculum, a tight bundle of leaves around their rosette to protect themselves from freezing weather. Generally speaking for the rest of the tropical species, they'll continue growing as long as conditions will allow. It should be noted that there does exist a dozen or so annual species.

        Most species of Drosera will flower before the end of their first year of growth, especially in cultivation. In nature, it can take 1-3 years depending on the species. The flowers are typically seen in early spring and will ripen to release seed within a few weeks to a month. Tropical species will flower profusely when in good conditions, almost non-stop. Most species are able to be self pollinated, but may require manual pollination. There are some sections of the genus that require genetically different parents in order to produce viable seed.

        As for total lifespan, that varies greatly species to species. Drosera usually are long lived perennials, persisting for an estimated 50 plus years. This makes them among some of the longest lived carnivorous plants, next to their distant relatives in Nepenthes. However, particularly in Asia and Australia, there are species uniquely adapted to only living a few months and flowering prolifically to maintain their populations year after year. In most cases, if you grow Drosera, you can expect to keep most species for a long time.

Issues Facing Genus

        Drosera face a litany of conservation issues. Due to them being globally present, it's hard for large scale efforts to raise enough awareness for individual species. What further complicates the problem is that some species are incredibly prolific and invasive in some countries. These two factors combine with the preexisting issues facing all carnivorous plants to make Sundews some of the most vulnerable carnivorous plant species.

        Being globally present is sadly an issue for Drosera conservation. It's easy to rally for the conservation of species when they are isolated and facing extinction. In the case of the Sundews, they have an incredibly large range as a genus. Very few species are extremely widespread, with most occurring in small ranges overlapped by their more frequent seen relatives. This makes it difficult to form a large body of public interest in protecting Sundews.

        On the other hand, due to hobbyist, some Drosera species like Capensis are invasive outside their native range. In New Zealand and parts of California in the United States, Drosera Capensis has been accidentally released and government programs have been put into action to eradicate this populations as they pop up. From the government officials perspective, Drosera can be seen as a nuisance. This only furthers the conservation challenges.

        As with all carnivorous species, human developments are the most destructive force. Drosera exist in very specific habitats that they've adapted to over large spans of geological time. This means restoration efforts usually fail, as the original habitat was a combination of many unique factors. Not only does the soil, water, weather, and light levels have to be appropriate, but also a large ecosystem of insect life is required to sustain these populations. Without a vibrant ecosystem, Drosera have a poor chance of establishing.