Dock, Broadleaf

Name:  Broadleaf Dock

Botanical Name: Rumex obtusifolius

Form: wildflower

Parts Used: seeds, greens

 

Citation: Guenther, K. (2020, January 12) Broadleaf dock as wildlife food [Web log post.] Retrieved: supply the date, from http://wildfoods4wildlife.com

Getting Started

Also known as bitter dock, broadleaf dock is 19th on our list of Super Seeds, a favorite of eastern towhees. It is a very easy beginner seed to forage because it is easy to identify and the seeds do not need much cleaning, if any. Also, dock leaves are eaten by cottontails and the large leaves mean you can gather a good quantity quickly off just a few plants. You can harvest some leaves then come back and cut more later in the season as the plant continues to grow. And next year!

The main drawback of dock is that it is high in soluble oxalic acids, so it should not be fed in too high a quantity, more as a garnish. That, plus it can be very hard to remove from a garden once it is established.

Polygonaceae (Buckwheat Family) 

Rumex (Genus)

Common name	Virginia Rumex Species	Origin	Rare Plant Status
Sheep sorrel	R. acetosella	non-native	Not rare
Pale dock	R. altissimus	native	Yes, in some states (not Virginia)
Clustered dock	R. conglomerates	non-native	Not rare
Curly dock	R. crispus	non-native	Not rare
Heart-wing sorrel	R. hastatulus	native	Yes, in some states (not Virginia)
Broadleaf dock	R. obtusifolius	non-native	Not rare
Fiddle dock	R. pulcher	non-native	Not rare
Swamp dock	R. verticillatus	native	Yes, in some states (not Virginia)

Virginia Botanical Associates. (Accessed January 2020). Digital Atlas of the Virginia Flora (http://www.vaplantatlas.org). c/o Virginia Botanical Associates, Blacksburg. 

USDA, NRCS. 2015. The PLANTS Database (http://plants.usda.gov, 31 January 2020). National Plant Data Team, Greensboro, NC 27401-4901 USA.

One growing in dry soil, another right in a stream.

Risks

Rumex spp. are high in a chemical constituent called oxalic acid.

Medical toxicologist, Sandra James-Yi, DVM, PhD, DABT, explained to me that “all plants contain oxalic acid— so the issue becomes one of quantity.” Soluble oxalic acid is present in a number of common foods animals and people eat. When digested, the oxalic acid enters the bloodstream. If the level of soluble oxalates in the blood is high, the acids can precipitate out of the blood by binding with calcium, and cause hypocalcemia, or low levels of calcium in the plasma. Ingested in large quantities over a long period, soluble oxalates can damage the kidneys. In extreme cases, it can be fatal. So soluble oxalate toxicity is generally one of quantity.”

It’s best to think of plants like dock with these oxalates as a treat or garnish, and offer them to your patients within an array of healthy food choices. And check with your veterinarian in any case where calcium issues are a large part of the patient management.

Leaf Description: Leaves are broad and heart-shaped at the base with a groove that runs the length of the leaf stem on the underside. Stems and leaf edges may be tinged with red. In early spring, collect greens before the plant grows and flowers, when they are tastiest and least fibrous and bitter. The leaves are basal—they all emerge from a center point in the ground—and the leaf edges (margins) are smooth (no teeth). Leaves are somewhat shiny.

Seed Size: Dock seeds are egg shaped with 3 paper wings attached perpendicularly to the seeds.

Harvesting

		Jan		Feb		Mar		Apr		May		Jun		Jul		Aug		Sep		Oct		Nov		Dec
		winter		winter		late winter		early spring		spring		late spring		early summer		summer		late summer		early fall		fall		late fall
seeds														x	x	x
greens							x	x	x	x	x	x

Does this lend itself as a good enrichment item?

Yes, for seeds. The best stalks to harvest for enrichment will have red-brown seeds but the stalks and leaves will still be very slightly green. If you wait longer than that and the leaves or stems are totally brown, the seeds will be very easy—too easy—to dislodge from the stem to be used for enrichment. But those loose seeds can still be offered as food. Stems are sturdy and can be cut and installed inside an enclosure for animals to glean the seeds off the stalks themselves. With care, stalks loaded with seed can be harvested and keep upright in a bucket without losing too many seeds in transport.

Harvesting Dock Seed:

You can harvest stalks for seed anytime the seeds are fully chestnut brown color. By the time the leaves and stems turn fully brown, the seed will be starting to fall off the stalks readily.

When harvesting for seed, I like to clip off the leaves, which are few, right in the field as I cut the stalk. Removing the leaves means now when you remove the seeds from the stem after the seeds have dried and cured, there will be less leaf debris to sift out, making for cleaner seed and less work.

You can easily pull the mature seeds off the stems by running the stalks through your hands. Work over a large paper sack or a sheet to collect the seeds.

It is easy to collect a large quantity of dock seed, even with just a handful of plants.

Harvesting Dock Greens:

Green leaves can be harvested at anytime spring to fall, but are tastier and less fibrous when young and small in early spring, before the plant sends up its main stem. Wash and refrigerate as soon as possible after harvest.

Other Species:

An extremely similar plant, curly dock (Rumex crispus), is another common, introduced dock that grows in the same habitat as broadleaf dock. For our purposes, I’m not sure there is any reason to differentiate the two species, and I don’t know if animals have a preference. However, if you are inclined to figure it out exactly which species you have, leaf width is the key. Broadleaf dock’s leaves are more oval and longer, up to about 30 inches long and the edges of the leaves lay fairly flat. Curley dock’s leaves are more spear-shaped, about 20 inches long and the edges of the leaves curve up to form ruffled edge.

Rare Species in Virginia:

None in Virginia.

Feed Dock to:

Book References

Elpel, T.J. (2013) Botany in a Day (APG). Pony, Montana: Hops Press, LLC.

Martin, A.C., Zim, H.S., Nelson, A.L. (1951). American Wildlife and Plants: A Guide to Wildlife Food Habits. New York: Dover Publications.

Scott, M. (2013). Songbird Diet Index. National Wildlife Rehabilitators Association, St. Cloud, MN.

Townsend, J. F. (2015, April) Rare Plants Natural Heritage Technical Report 15-10. (Unpublished Report) Richmond, Virginia: Virginia Department of Conservation and Recreation, Division of Natural Heritage. 

Online References

USDA, NRCS. 2015. The PLANTS Database (http://plants.usda.gov, 15 February 2020). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Virginia Botanical Associates. (Accessed January 2016). Digital Atlas of the Virginia Flora (http://www.vaplantatlas.org). c/o Virginia Botanical Associates, Blacksburg. 

Personal Communication

James-Yi, S. DVM, PhD, DABT, DABT. (2017, September) Personal interview with medical toxicologist at NOW Foods.