Carex atrata - Laîche noirâtre, Carex noirâtre

Carex atrata, the black sedge, is recognisable by its short, almost black spikes, which nod above a clump of fine, fresh green foliage. This summer flowering, highly visible, distinguishes this species from many sedges grown mainly for their foliage. Very resistant to cold and wind, this mountain perennial finds its place in a cool rock garden or a border. It is a plant for cool climates or alpine gardens. It thrives in well-drained soil that does not dry out in summer.

The genus Carex belongs to the Cyperaceae family: plants in this group resemble grasses but do not belong to the Poaceae family. It is a herbaceous perennial; its foliage is deciduous: it develops during the growing season, dries with the onset of cold weather, then regrows from the crown in spring. This wild species has a vast natural distribution range, from Greenland to Europe and into temperate regions of Asia. In France, it is found in the mountains, in subalpine and alpine lawns, heathlands, and certain cool, rocky slopes. It tolerates long snow cover and grows in full light, in soils poor in nutrients, cool to moist, but not marshy. Short rhizomes produce a dense clump that slowly widens. The leaves, 3 to 5 mm wide, are linear, supple, and light green, sometimes slightly glaucous. They remain distinctly shorter than the flowering stems. These are erect, slender, and triangular in cross-section, a typical characteristic of Carex; their tips nod under the weight of the spikes. The plant reaches 30 to 40 cm in flower, with a 30 to 40 cm spread, the foliage remaining lower. Flowering occurs between June and August, depending on altitude and climate. Each stem bears three to five spikelets, oval or cylindrical, 1 to 2 cm long. They are made up of numerous tiny flowers lacking decorative petals. Initially close together and more or less erect, the lower spikes become pendulous at maturity. Their purplish-brown to blackish scales are the origin of the Latin epithet atrata, meaning 'blackened' or 'clothed in black'. The fruits, enclosed in small utricles, take on a tawny to dark brown hue. Described by Linnaeus in 1753, this sedge is an arctic-alpine species of cold grasslands. Its hardiness drops below -25 °C. In lowland areas, its success depends mainly on soil retaining moisture and a position sheltered from scorching sun. It tolerates slightly acidic to neutral soils, as well as a little lime.

In a cool rock garden, this mountain sedge can be planted in small groups between stones in a pocket of deep, slightly moist soil. It can also be used to vegetate a north- or east-facing bank and a low meadow. You can pair it with Carex davalliana in the wettest part, with Primula denticulata 'Alba', Trollius 'Lemon Supreme', and Geranium sylvaticum 'Mayflower'. Their white, lemon-yellow, and blue-mauve flowers naturally surround its dark spikes.