Polygonaceae-dock2017-08-17T17:51:40+00:00

Polygonaceae: Knotweed Family — Rumex (Dock)

Docks are identified not by their flowers (which might reasonably be described as inconspicuous) but by their leaves, their growth habit and, above all, by what used to be described as “valves” but are now more accurately described as “perianth lobes”. There are 6 perianth lobes, the outer 3 inconspicuous, the inner 3 larger and clearly visible.  Callosities (small white lumps) may be present on one or more of these inner perianth lobes; their number and size are important diagnostic features. In some cases it is impossible for the non-expert to identify species without being able to see the mature perianth and its callosities.

Sheep Sorrel– Rumex acetosella

Blooms:

Apr–July

Plant Height:

< 40 cm

Flower Size:

Very small

Origin:

Eurasia

Invasive?

Yes – moderate

Habitat:

Open grassland, disturbed places

Notes:

Despite its common name, this plant is urelated to the sorrels (Oxalis family) but closely related to the docks. Unlike the docks, it has small but rather beautiful flowers despite appearing at first sight as a rather nondescript brownish red plant of no great interest. The plant is dioecious with male and female flowers on separate plants. The leaf blades are mostly basal and easily identified by their two backward facing lobes.

Clustered / Green Dock – Rumex conglomeratus

Blooms:

May–Aug

Plant Height:

30–80 cm

Flower Size:

Small cluster

Origin:

Europe

Habitat:

Low moist places

Notes:

One of the more common docks, with leaves that are long and slender, reducing in size as they ascend the stem.  The flowers are in small interrupted clusters, all but the uppermost with subtending leaves – an important diagnostic feature. Callosities are present on all of the inner perianth lobes, more or less equal in size and almost as wide as the lobes.

Coastal Willow Dock – Rumex crassus

Blooms:

Feb–July

Plant Height:

20–60 cm

Flower Size:

Large cluster

Origin:

Native

Habitat:

Coastal dunes & bluffs

Notes:

The stem of this dock is generally prostrate with the tip ascending (unlike the generally erect Willow-leaved Dock (Rumex salicifolius)). Its leaves are also slightly shorter and wider, normally flat but may be wavy-edged. The inflorescence is generally dense. The inner perianth lobes are wide to narrowly ovate, rounded or truncate at the base. There is a single callosity which may be about as wide as the lobe.

Curly Dock – Rumex crispus

Blooms:

All year

Plant Height:

40–100 cm

Flower Size:

Large cluster

Origin:

Eurasia

Invasive?

Yes – limited

Habitat:

Grassland and waste places

Notes:

A very common and invasive dock. This has leaves with strongly wavy edges and one or more dense inflorescences which more or less hide the stem. The inner perianth lobes have smooth edges. Callosities are present on all of the inner perianth lobes, one being larger than the others but all being < 1/3 as wide as the lobes.

Fiddle Dock – Rumex pulcher

Blooms:

May–Sept

Plant Height:

20–60 cm

Flower Size:

Small cluster

Origin:

Mediterranean

Habitat:

Disturbed areas, grassland, dry or moist places

Notes:

This common dock is most easily recognized by its growth habit, with an erect stem and slender branches growing out at right angles. Callosities are present on each of the inner perianth lobes. The lobe margins are conspicuously toothed, each with 2–5+ teeth.

Willow-leaved Dock – Rumex salicifolius

Blooms:

May–July

Plant Height:

30–60 cm

Flower Size:

Large cluster

Origin:

Native

Habitat:

Moist places

Notes:

This has ascending to erect stems with moderately dense inflorescences that are both terminal and axillary. The leaves are long and slender, lanceolate to linear, 5–13 cm long and 1–2.5 cm wide.  Leaf margins may be either flat or wavy. The inner perianth lobes are triangular with the base either tapered or truncate. There is a single callosity which can be about as wide as the lobe.

Willow Dock – Rumex transitorius

Blooms:

Apr–June

Plant Height:

25–70 cm

Flower Size:

Large cluster

Origin:

Native

Habitat:

Moist places, pond margins

Notes:

This is similar to Willow-leaved Dock (Rumex salicifolius) but has stems that are decumbent to erect. Its leaves are slightly broader (6–15 cm long and 2–4 cm wide), usually with wavy margins. The inflorescence is dense, more interrupted towards the base and without the subtending leaves found in Clustered Dock (Rumex conglomeratus) with which this might sometimes be confused. The inner perianth lobes are variable in shape. There are generally 3 callosities of varying sizes.