"Typical" no-locality form of D. rotundifolia in spring growth.
Range: Circumboreal temperate distribution, Philippines, New Guinea
The round-leaved sundew is perhaps the most widespread sundew, and one of the most widespread carnivorous plants, on earth. Found throughout bogs and fens in northern North America as far south as central California, Colorado, and northern Mississippi and Georgia and up into the Arctic Circle, as well as nearly all European countries (including Iceland) and the northern portions of Asia. Two unique tropical outlying populations are also recorded from Mindanao, and the western end of New Guinea. Habitats tend to be very moist to occasionally flooded; sphagnum bogs, muck flats, seeps, fens, and similar low-nutrient locations with open sunny spaces. Plants tend to be largest in spring, averaging between 6-8 cm in diameter but capable of reaching nearly 18 cm across in certain cases, flat rosettes (especially later in the year) or semi-erect with paddle-shaped leaves. Petioles are long, flattened and slightly tapered up toward the lamina, glabrous or bearing a number of small wispy white hairs. Lamina are somewhat uniquely orbicular, sometimes slightly triangular or ovate in shape but most typically broader than long, up to 3 cm in diameter. Coloration may be entirely green to nearly solid red in strong light or cool conditions. Inflorescences are glabrous and up to 20 cm tall, bearing up to 25 blooms. Flowers are up to 1 cm in diameter, generally very small with obovate or spathulate petals that are white in nearly all populations (rare individuals with pinkish veins, one population recorded with pink petals in Japan, possibly a trait picked up from complex backcrossing through D. tokaiensis with D. spatulata). This species is readily distinguished from most others by the very petiolate leaves and broader than long lamina, and from capillaris where they co-occur also in generally broader more rounded lamina, potential for hairy petioles, and elongate rather than ovoid seeds from white (not pink) flowers.
Cultivation: grow in pure peat, sphagnum, or a 1:1 peat/perlite soil, kept very moist to wet and humid, with temps of 60-85°F in summer; most forms generally do best when kept cooler, very hot conditions will result in collapse. In winter, when most forms go dormant, let pot dry to moist and place in a cold area for 3 months or until spring. Hibernacula are generally frost-tolerant. Tropical forms should be kept cool but in constant conditions year round. Sow seeds on soil surface, and give a 4-6 week cold stratification (except in tropical forms), and grow in strong artificial light to full sun.
Lifespan and reproduction: perennial. Reproduces through seeds, and can be grown through leaf cuttings.
Sources: Lowrie et al. (2017). Drosera of the World Vol. 2. Redfern Natural History Publishing
"Typical" form spring growth and flower. Blooms are very small relative to the plant on average, and self-fertile.
D. rotundifolia "Nieuwkoop, Netherlands"
I personally have found this species touchy to deal with long-term, unless changes in photoperiod and temperature are both provided. Plants form hibernacula with difficulty when day length remains consistent year-round, as in a stable greenhouse setting, and do not appreciate much heat and so grow best on lower levels or in a highland type setup. Outdoor bog gardens are ideal for this species particularly in more northern areas, however indoors if they can be moved in front of a window in winter to reduce light and temperature, triggering dormancy may be more reliable.
D. rotundifolia from Baranof Island, Alaska. This form has been particularly sensitive to improper conditions, needing it very cool, and has more slender, extremely hairy leaves.