D. intermedia "Carolina Giant" form
Range: Europe, southeast Canada, Eastern US, Cuba, South America
Sometimes referred to as the “water sundew” (along with several other nicknames frequently shared with other sundew species and as such unusable), this is a widespread and rather variable species, found from the western edges of Russia across most of Europe in nearly every country, through the eastern half of North America, and then across the Caribbean into Cuba as well as regions of northeastern South America as far south as northern Brazil. Across its range it is a relatively cosmopolitan plant, not particularly picky about its soil types but nearly always growing in the wettest parts of its habitat, from soaked sphagnum or sand seeps to entirely aquatic on floating mats of vegetation. Occasionally, it may also be submerged for significant periods. Plants vary in size, from acaulescent rosettes directly at ground level to stem forming up to 15 cm in height, topped by a semi-erect rosette of leaves that slowly fold downward over time. This rosette averages between 4-8 cm across, though in some large variants may exceed 12 cm. Leaves are slender and paddle-shaped, with a very thin glabrous petiole that tapers from base to lamina, and the lamina is obovate to spatulate, tapering slightly from tip down to the petiole. Coloration may vary from purely green with pink tints to the tentacles (or all green in anthocyanin-free forms) to solid red throughout. Inflorescences grow out from the side of the rosette and up, reaching to 15 cm in height, and are entirely glabrous. Up to 10 blooms may be supported opening one after another, flowers up to just over 1 cm wide with pure white, with narrowly obovate petals. In temperate parts of its range this species dies back to a dense hibernaculum of curled leaves, though is evergreen in the tropics.
This species is readily separated from others in range by its glabrous petioles and inflorescence, semi-erect leaf habit (rather than flat or fully erect), and inflorescences that emerge laterally from the rosette.
Cultivation: grow in any suitable sand/peat soil mix, kept very moist to flooded at all times, moderately humid with temperatures during the summer season of 70-95°F. Tropical forms should be grown at these temperatures year round, but in winter or whenever plants begin to develop hibernacula, temperate forms should be placed into cool to cold conditions for at least 3 months or until spring; skipping dormancy can kill them. Sow seeds on the soil surface, provide a 4-6 week cold stratification for temperate forms, and grow in strong artificial light to full sun.
Lifespan and reproduction: perennial. Reproduces through seed and natural divisions, and can be grown through cuttings.
Sources: Lowrie et al. 2017. Drosera of the World.
D. intermedia from Easton, Massachusetts. Smaller than the Carolina form and slightly more compact, but otherwise very similar.
D. intermedia Anthocyanin-free form. This temperate form grows similar to the other temperates shown above, but completely lacks all red pigmentation. It also has a slight tendency to grow smaller than the Easton or Carolina plants, at only around 2 inches across maximum.
Tropical form from Luepa, Bolivar, Brazil. This is one of the more robust tropical forms I've seen, rivaling my Carolina form in diameter though has a slight tendency to grow more erect, and a bit redder. Plants and seeds have no need for a cold period.
The form from Roraima State, Brazil has long been mislabeled as originating from Mount Roraima, where D. intermedia has not been recorded growing. Like the Luepa form above, it is evergreen, and a bit redder than my temperates tend to express, but is a smaller plant with a seemingly shorter lifespan, often surviving only a couple of years before dying away and letting seeds regrow the colony.
D. intermedia "Carolina Giant" x "Roraima State, Brazil." A cross between a large temperate and a small tropical plant, this intraspecies hybrid I made myself, and has thus far proven to be one of the largest intermedia I have yet seen, dwarfing even my healthiest Carolina plants, and maintains an evergreen growth habit thus far without need for dormancy. Seeds are likely to not need stratification either.