Euphorbia cornigera

Euphorbia cornigera, commonly called the horned spurge, is a Himalayan perennial recognisable by its reddish stems, its foliage traversed by a pale vein and its lemon-yellow inflorescences. These appear in summer and form large clusters above the clump. Its ample, upright vegetation finds its place in the middle or at the back of borders. Easy to pair, undemanding, it brings light to naturalistic, rural or contemporary gardens.

This species belongs to the family Euphorbiaceae. Its most common name in horticulture is horned spurge. Euphorbia pilosa var. cornigera is its only botanical synonym. This botanical species is native to northern Pakistan and the western and eastern Himalayas, where it grows in temperate mountain regions. It is a herbaceous deciduous perennial: its stump lives for several years, while the stems and leaves die back in winter and regrow in spring. Its habit is initially upright, then the clump widens at the top. Of medium-fast growth, the plant reaches its mature size in two to five years. It measures 75 cm to 1 m in height when in flower and 60 to 90 cm in spread. In good garden soil, it can approach 1.20 m. The stems, robust and tinged with red, bear alternate leaves, narrowly oblong to lanceolate, 3 to 7 cm long. The dark green lamina is traversed by a midrib pale green to almost white. In June and July, the branched stems terminate in large clusters of lemon-yellow to yellowish-green. As with all spurges, what we take for a flower is an inflorescence composed of tiny petalless flowers, gathered in a small cup called a cyathium. The colourful bracts that surround them are more decorative than the flowers. This flowering provides nectar and pollen to many insects. After pollination, capsules divided into three locules form. At maturity, their surface becomes covered in small cylindrical outgrowths, the origin of the name cornigera, 'which bears horns'. This species was described by Edmond Boissier in 1862 and has received the Award of Garden Merit from the Royal Horticultural Society. Like other spurges, it contains a white latex that is irritating to skin and eyes, and harmful if ingested. Its hardiness is of the order of -10 to -14°C at its peak in well-drained soil.

In a border, this horned spurge benefits from being planted in groups of three or isolated among lower perennials. Pair it for example with the garden iris 'Sultan's Palace' which offers large velvety red-brown flowers, with the woodland sage 'Schwellenburg' for its purplish-pink spikes and with the eryngo 'Blauer Zwerg' for its metallic blue heads. At the end of the season, the aster 'October Skies' takes over with its lavender-blue daisies. These four varieties enjoy sun and well-drained soils. They will fit into a natural, mineral or contemporary garden, with successive blooms from spring to autumn.