Rumex altissimus (Pale Dock)

Plant Info
Also known as: Tall Dock
Genus:Rumex
Family:Polygonaceae (Buckwheat)
Life cycle:perennial
Origin:native
Habitat:sun; moist, disturbed soils; ditches, roadsides, swales, wet fields, marshes, shores, riverbanks
Bloom season:May - June
Plant height:2 to 4 feet
Wetland Indicator Status:GP: FAC MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 3-petals Flower shape: indistinct Cluster type: panicle Cluster type: whorled

[photo of flower clusters] Branching clusters at the top of the plant, each branch with numerous whorls of 10 to 20 slender-stalked flowers, the lower whorls on a branch more widely separated than those near the tip. Flowers are up to ¼ inch long (4.5 to 6 mm), light green, 3-sided with 2 series of tepals (petals and similar sepals) and the outer tepals much smaller than the inner.

[photo of grains] The 3 inner tepals, also called valves, are triangular to heart-shaped, slightly longer than wide, veined across the surface, the edges mostly flat and smooth or slightly jagged. At the base of 1 inner tepal is a projection called a grain, at least half as long as the tepal at maturity, lance to narrowly egg-shaped with a blunt tip; grains are usually absent on the other two tepals or sometimes one is poorly developed. Tepals are spreading at flowering time, revealing stamens and styles, and close up after pollination. Flower stalks are very slender and smooth, about as long as the inner tepals with a joint near the base.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of leaves] Leaves are all alternate, 4 to 10 inches long, up to 3 inches wide (2.5 to 4 times as long as wide), lance-elliptic, hairless, toothless, somewhat shiny, pointed at the tip, usually wedge-shaped at the base, with a faint network of veins and mostly flat blades, the edges slightly wavy but never crinkled. The lowest leaves are largest and long-stalked, becoming smaller and shorter stalked as they ascend the stem.

[photo of ocrea, shoot and stem] At the base of the stalk is a brownish papery sheath (ocrea) that surrounds the stem and mostly disintegrates with maturity. Stems are light green, stout, erect, hairless, ribbed, and unbranched or few-branched, often with short shoots or leaf clumps in the axils just below the flower clusters or near the base.

Fruit: Fruit type: capsule/pod Fruit type: seed without plume

[photo of mature fruit] A flower produces a single seed, wrapped in the persistent tepals, which form a capsule-like structure and dry to brown.

[photo of seed] Seeds are 3-sided, egg-shaped with a short taper at the tip, dark reddish brown, and 2 to 2.8 mm long.

Notes:

Pale Dock is a native species of moist, usually disturbed soils and reaches the northern edge of its range in Minnesota. There are at least 11 similar Rumex species in the state, 5 of which are native. Some of the distinguishing characteristics are whether the leaves are crinkly-wavy or relatively flat, the shape of the inner tepals at maturity, size and shape of the grains, whether the grains on all 3 inner tepals are about the same size, sometimes the length of the flower stalk or where the stalk is jointed or the vein pattern on the leaves. Pale Dock has flat leaves that may be somewhat wavy but never crinkled along the edge, mostly triangular tepals up to 6 mm long, usually a single grain half or more as long as the inner tepal, the flower stalk jointed near the base, and a faint network of lateral leaf veins.

The flat leaf blades, single grain, and lack of a rosette of basal leaves distinguish it from all of the Rumex species with more strongly crinkled-wavy leaves, Curly Dock (Rumex crispus) being the most common. The most similar species are Mexican Dock (Rumex triangulivalvis) and Swamp Dock (Rumex verticillatus), both of which also have flat leaves. R. triangulivalvis has proportionately narrower leaves (5 to 6 times as long as wide), tepals about half the size (to 3mm long) and grains on all 3 tepals, though one may be larger than the other two. R. verticillatus has more loosely arranged clusters of long-stalked flowers and tepals up to 5 mm long that are broadly egg to diamond-shaped to 3-lobed and more rounded at the tip. Patience Dock (Rumex patientia) may have relatively flat leaves, but the tepals are larger (to 8 mm long), round to kidney-shaped, and typically have a single, tiny grain on each flower.

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More photos

Photos courtesy Peter M. Dziuk taken in Fillmore and Scott counties.

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