Rheum alexandrae - Alexander's Rhubarb

The Rheum alexandrae, also known as Alexandra's Rhubarb, is a Tibetan cousin of our native rhubarb, but easy to acclimatize in our gardens if it has a humus-rich soil that remains moist throughout the year. From a rosette of green leaves veined with white emerges a spectacular inflorescence in summer, resembling a vegetal tower, covered with beautiful bracts in a pale greenish cream color, overlapping each other and reaching the size of a hand. In autumn, the foliage is painted with shades of fire and the bracts with red streaks, creating a stunning effect. Place this botanical curiosity near a pond, a stream, or in a constantly fresh large rockery.

The Rheum alexandrae, from the Polygonaceae family, is native to the Himalayan region of Asia. It is found specifically on alpine banks in Tibet, western and southern China, where it always grows near watercourses, in marshy areas, or sometimes on very wet slopes or between damp rocks, between 3000 and 4600 meters (9842 and 15092 feet) above sea level. This rhubarb has a relatively slow growth. It dislikes summer heat like most high mountain plants. On the other hand, it has good hardiness under a thick snow cover or under protective mulch.

It is a perennial plant with a deep rhizome that develops a rosette of modest-sized leaves for a rhubarb from spring onwards. At maturity, the rosette will not exceed 30-40 cm (12-16in) in height. The leaves, which are oval to elliptical in shape, sometimes pleated, are 9 to 14 cm (4 to 6in) long and 6.5 to 9 cm (3 to 4in) wide. They are carried by a petiole 10 to 14 cm (4 to 6in) long, initially upright and later drooping. The lamina is pale green and traversed by 3 or 4 clearly visible white veins. Flowering occurs in June-July and is highly ornamental for 2 to 3 months. Floral stems emerge from the leaf tuft, standing from 90 cm (35in) up to 1.50 m (5ft) above the ground depending on the growing conditions. Each floral stem is a panicle of tiny flowers hidden under large pendulous bracts in a pale greenish cream color, arranged like tiles, with decreasing size from bottom to top. With a parchment-like texture, they remain decorative for a long time and become streaked with red towards the end of the season. The fruits (trigonous and winged achenes) will ripen 2 months after the start of flowering. The foliage, before disappearing, also takes on beautiful copper-orange colors.

In addition to their well-known culinary qualities, rhubarbs are also key elements for the ornamentation of a colorful flower bed, an exotic garden, or even an ornamental vegetable garden. The Alexander rhubarb appreciates humus-rich, non-calcareous, loose, deep, and moist soils. Therefore, it will naturally find its place in a mountain garden (or in a cool climate), not far from a water source that will guarantee its constant freshness. It is a spectacular perennial plant during flowering, to be highlighted alongside Primula bulleyana or candelabra primroses. Place it at the back of a flower bed or against the south or west wall of a house. Its exotic, if not strange, appearance blends very well with polygonums, hostas, and carex.