Growing form
Perennial herb, rhizome creeping.
Height
60–200 cm (25–80 in.). Stem grooved, unbranched until inflorescence.
Flower
Regular (actinomorphic), approx. 2–3 mm (0.08–0.12 in.) across, bisexual, wind-pollinated. Perianth-segments in two whorls of three. Segments of outer whorl small, recurved. Inner whorl forms fruit valves, which are roundly kidney-shaped, wider than long, with cordate base, margins entire or with slightly rounded teeth (crenate), and usually without tubercles. Sometimes one segment has an elongated pimple along the midrib. Stamens 6. Pistil of 3 fused carpels, styles 3. Joint on flower-stalk near base. Flowers whorled. Inflorescence an abundantly branched, dense and long compound raceme.
Leaves
Basal leaves like in rosette, stem leaves spirally. Leaves long-stalked, hairy underside along veins. Leaf blade roundish–broadly ovate (20–30 cm (8–12 in.)), as long as broad.
Fruit
Brown achene, 2.5–3 mm). Perianth segment 4–5 mm (1.6–2 in.) wide, 3-lobed, without tubercles. Lobes with cordate base and almost entire margins. Fruit-stalk thickening at end, 2–3 times longer than calyx (3–15mm), node in basal part.
Habitat
Roadsides, yards, gardens, behind cow-sheds.
Flowering time
July.

Genus Rumex is a botanically difficult group because its species cross-breed easily. Ripe fruit is required to make a sure identification. Monk’s rhubarb is still very rare in Finland, and it is relatively wide-leaved compared to its relatives. Of the genus Rumex plants that grow in Finland, only Asiatic dock (R. confertus) and Scottish dock (R. aquaticus) have similarly broad basal leaves.

Genus Rumex species grow mainly in temperate zones in the northern hemisphere, where they number approx. 200 species. Monk’s rhubarb is quite common in central and southern Europe, but in Finland it is at the northernmost reach of its habitat. It is cultivated in gardens as a substitute for spinach, although not so much in Finland. Its leaves taste quite bitter in the middle of summer, and are at their best in spring and autumn. Leaves can also be dried for later use, and the root is dried as a dying agent. Apart from people, caterpillar grubs have also acquired a taste for plants in the genus.

Taxonomi

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Tribus

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Art