Rhizomatous herb or subshrub to 25 cm. Stems green, four-angled, appressed-pubescent, nodes four to six, internodes longer towards top of plant, branch only at apical node. All leaves but those at the uppermost node non-chlorophyllous, scalelike and caducous; those at uppermost node deciduous or persistent, in a whorl of four to six, 2–7 × 1–4.5 cm, elliptic, ovate, obovate or rhombic, upper surface green, appressed pubescent, lower surface pale green, pubescent with appressed trichomes or glabrous, two to three secondary veins on each side of the midvein, margins entire, apex acute to shortly acuminate; petiole to 0.2 cm long. Inflorescence compound cymose, 12–40-flowered; bracts four, ovate, 0.5–1.5 × 0.5–1.5 cm, petal-like, greenish white to white, occasionally tinged red to purple, apex acute to acuminate. Flowers with petals 0.1–0.2 cm long. Fruit a red drupe, 5–15 per infructescences, globose, 0.6–0.9 cm diameter, stone ovoid, smooth, apex rounded. Flowering May to August, fruiting August to October. (Xiang & Boufford 2005; Noshiro 2012; Murrell 2015; Wahlsteen et al. 2020).
Distribution Canada Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Northwest Territories, Nova Scotia, Nunavut, Ontario, Quebec, Saskatchewan, Yukon China South Jilin Japan Hokkaido, Honshu, Shikoku North Korea Russia Far east United States Alaska, Colorado, Connecticut, Idaho, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming Saint Pierre and Miquelon Greenland
Habitat Dry to moist broadleaf or coniferous forests, subalpine, boreal coniferous forests, wood margins, roadbanks, marshes, and bogs, from 0–3400 m asl.
USDA Hardiness Zone 2-7
RHS Hardiness Rating H7
Conservation status Not evaluated (NE)
Of the four members of subgenus Arctocrania, Cornus canadensis is the most frequently cultivated, being the most heat-tolerant species – but that tolerance is still strictly limited, and many gardeners will find it a challenge to grow. Wherry (1934) found that its distribution was limited to areas where the mean summer temperature does not exceed 18.3°C; the further south in its range, the higher in elevation it grows. In addition it needs cool, moist acidic soil. In British gardens it is generally considered a plant for woodland gardens, where such conditions can be provided, but in the wild it often grows in full sun, forming floriferous carpets. Cappiello and Shadow (2005) discuss its cultural requirements at length and stress the need for finding the most appropriate ecological provenance for planting stock, at least in North America. In Maine Paul Cappiello trialled 30 clones and found that one, ‘Downeaster’, was the most tolerant and suitable for wider cultivation. So far as is known, there are no named selections in cultivation in Europe and the provenance of cultivated stock is unrecorded.
Once established in conditions that suit it, however, Cornus canadensis can spread far and wide, forming large carpets of the attractive whorls of (usually) four leaves and similarly quadripartite ‘flowers’, though flowering has good and bad years. It does not like to be overshadowed by taller herbaceous or shrubby plants, though high tree shade is acceptable and probably often necessary. It finds such conditions in Ray Wood at Castle Howard, North Yorkshire, and forms patches tens of square metres across there, flowering in May and June, though fruits are very rare here. Where they are set, they form clusters of red berries that are an important source of nutrition for wildlife, and can be eaten by humans (though they are considered to be rather insipid). REF
Difficult to grow outside its natural range as it dislikes high temperatures and anything other than highly acidic soils. Propagation works well by several methods. Seeds should be extracted from fresh fruits and scarified, followed by 90 to 120 days cold stratification, the longer the better. Softwood cuttings treated with 3000–5000 ppm K-IBA and kept under intermittent mist will root well. Mature plants can also be divided during the cold season (Cappiello & Shadow 2005).