Veterinary Medicine Library

Poke or Pokeberry or Pokeweed
(Phytolacca americana L.)
(= P. decandra L.)

Description | Distribution | Conditions of poisoning | Control | Toxic principle | Clinical signs | References


Poke or Pokeberry

Description

Poke is an erect, branched, smooth herb with coarse, succulent, purplish stems; at maturity it is 3 to 10 feet tall. Its leaves, borne on short stalks, are alternately placed and ovate and are without teeth on their margins. Leaves grow up to about 5 inches long. Poke bears small white flowers on short flowerstalks along separate branches at the growing tip of the plant and in the axils of the leaves. Each flower becomes a dark purple berry, flattened and spherical. The berries contain crimson juice and about 10 seeds each.

A perennial, poke comes up year after year from an enormous taproot but it is spread only by seed.


Pokeweed in Bloom Pokeweed Fruit in Midsummer
     In Bloom     Fruit in Midsummer  

Distribution

Poke is a herbaceous perennial and is native to North America. Though considered as a weed in Illinois, it is the source of food in some regions of the country. Its habitat ranges from the New England states to Florida and as far west as eastern Nebraska. Poke is frequent in open woods and occurs in waste places, along fencerows, about farmsteads, in pastures, if the soil is especially moist and rich.


Conditions of poisoning

Cattle and sheep are the most susceptible species but poisoning occasionally occurs in horses, goats, and pigs. Animals may feed on poke plants, especially in the spring, when the plants are succulent. Where grass is short, the animals may browse so close as to get the top parts of the poke roots. Unless green herbage is very scarce later in the summer, animals will avoid the tops and berries.


Control

Animals should not be grazed in pastures infested with poke, especially in the spring or during dry, hot periods. The most certain way to eliminate poke from wooded pastures, where the plants are likely to be numerous and where it may be difficult or impossible to use chemical weed-killers, is to dig the individual plants out by their roots. As poke is spread only by seed, it is important to destroy the plant before flowering.


Toxic Principle


Clinical signs

The eating of nonfatal quantities of poke, perhaps of the shoots, may cause retching or vomiting after two hours or more. These signs may be followed by dyspnea, perspiration, spasms, se

vere purging, prostration, tremors, watery diarrhea (often bloody) and, sometimes, convulsions. If a fatal quantity is eaten, perhaps including roots, the above signs are followed by paralysis of the respiratory organs and other narcotic effects, culminating in the death of the poisoned animal.

In pigs:

In Cattle:

Other References:

Pokeberry entry in Wikipedia

Phytolacca americana entry in Wikipedia


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