Drosera capensis,
the Cape sundew
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Drosera capensis is commonly known as the Cape sundew. It is a small rosette-forming carnivorous species of perennial sundew native to the Cape in South Africa. Drosera capensis is one of the most common sundews in cultivation due to its size, the ease of growing it, and the vast amount of seeds it produces.
Drosera capensis has strap-like leaves covered with bright-colored tentacles. These leaves typically grow up to 1.4 inches in length (not including the petiole) and 0.2 inches in width.
In its native South Africa, Drosera capensis flowers during the summer months (December and January). The flowers on the plant self-pollinate when they close and produce a large volume of small spindle-shaped seeds. The seeds release from the capsules when the flowers die. Drosera capensis flourishes in locations with full sunlight and nutrient-poor soil containing lots of water and no lime.
Drosera capensis engages in predation through the use of its leaves. The plant captures its prey by attracting it with digestive secretions produced on the tentacles of each leaf. The secretion attracts the prey because of its shininess in sunlight and chemical components. When prey becomes trapped in the tentacles, all of the tentacles surrounding the victim will align and wrap themselves around the prey. This reaction from the plant is known as thigmotropism. This movement assists with digestions by increasing the prey's contact with digestive glands. It takes the plant up to one hour to fully enclose the prey.
After the initial capture, the digestion of the prey takes at least 6 hours. The digestive secretions aid in decomposing the prey until only chitin armor remains. Nutrients absorb through the tips of the tentacles, the same location as the secretion production. Once the prey decomposes, leaving no remaining nutrients, the leaves and tentacles return to an opened position.
Drosera capensis' prey typically consists of insects and arthropods. The plant's secretions are the key to trapping prey. The secretion contains mucin, which includes 4% of an acidic polysaccharide in an aqueous solution with a pH of approximately 4. Mucin has a high viscosity, similar to syrup. Mucin is stretchable up to a meter in length.
In late spring or early summer, Drosera capensis flowers, producing many small pink flowers containing five petals each. These petals appear at the end of scapes, long internodes, that are up to 1 foot long. The plant's flowers open at different times in the morning and close before mid-afternoon. These flowers last only one day each and new ones open the next day. The plant produces a plethora of seeds inside capsules that are immediately available for sowing or storage in cold, dry conditions for over a year. The seeds release from their receptacles when they are ready and ripe and scatter near the parent plant. The image to the right depicts the small pink flowers, along with the following days' closed flowers and the tentacles in the background.
Multiple different varieties of Drosera capensis exist, including wide-leaved, narrow-leaved, red-tentacled, and white-tentacled, also known as, Drosera capensis albino. Typically, Drosera capensis develops with wide leaves and a scrambling stem. Although it usually has broad leaves, the wide-leaved variation of the plant has leaves greater than 50% wider than the standard version. On the other hand, the narrow-leaved variety seldom produces tall stems and has thinner and longer leaves. Additionally, the narrow-leaved species has less hair on the plant throughout. Drosera capensis albino mirrors the appearance of the typical Drosera capensis plant but lacks the prominent red pigmentation featured on the tentacles. The flowers of this variety, blossom in a solid white color and the trichomes develop in clear or pink. The red variety of the plant becomes a unique blood-red color in full sunlight and has leaves like the narrow-leaved species. All of these varieties are commercially available for purchase for those interested.
There are many ways to create Drosera capensis plants. Some production methods include seed, leaf cuttings, and root cuttings. Drosera capensis survives very well in short-duration extreme temperatures and does not experience a dormancy phase like some other sundews. This species is well-known for being an easily-maintainable carnivorous plant in an indoor environment. It will thrive on a sun-filled windowsill with open-air and access to one to two inches of mineral-free water.
The optimal substrate needed to grow Drosera capensis consists of 70% blonde peat and 30% calcareous sand. The best temperature in the winter is between 41°F and 59°F, and the best temperature in the summer is between 68°F and 104°F. The plant requires that the soil is damp year-round through the use of a saucer underneath the pot. Although, in the winter, the plant requires less water and no saucer underneath the pot. A high ambient humidity ensures the continual production of mucilage. The plant is best suited for full exposure to the sun.
Drosera capensis appears on New Zealand's National Pest Plant Accord as an invasive species. As a member of this list, Drosera capensis is not purchasable from any plant retailers and is not tradable between plant owners. Drosera capensis now exists in the wild as a result of intentional planting or unintentional contamination from seeds of houseplants. The species is rapidly spreading in the wild both naturally and with the assistance of water birds.
In addition to New Zealand, Drosera capensis populated New South Wales in Australia. While it hasn't spread further, it is very important to monitor the distribution of species to ensure it doesn't overtake natural species. In California, Drosera capensis classifies as a natural weed. It also spread to peat bogs in South America, making it discoverable on multiple continents and classifying it as an invasive species.