Weed du Jour – Common Pokeweed

If there’s one weed that I should have under control, it’s common pokeweed (Phytolacca americana). This large weed is easily controlled with cultivation if you don’t allow it to become established. But there are two places where I’ve found this perennial weed growing – the raspberry bed and the asparagus bed.

Young Pokeweed in Asparagus Bed

Young Pokeweed in Asparagus Bed

It’s not surprising that these are the two places where pokeweed has established itself. I try my best to keep these beds free from weeds but when the raspberries are tall and the asparagus has reached its 5′ height, I tend to miss some of them. Pokeweed is one I missed.

Pokeweed is a huge plant, growing from 3-10′ tall, that tends to grow in hedgerows, by fences, along the edges of fields and in other places where it can grow undisturbed, i.e. asparagus and raspberry beds! The plant is propagated by seeds that can remain viable in the ground for 40 years. The seeds spout in spring and early summer and grow quickly into large plants. But what you don’t see is that the plants are also growing a large taproot that can be 4″ wide and 12″ long. The leaves of pokeweed are either egg or lance shaped, often with a reddish tint on the underside as they mature.

Pokeweed Inflorescence

Pokeweed Inflorescence

In the summer pokeweed developes inflorescences that are long and covered with small white flowers. These flowers develop into berries that are a dark purple/black when mature. Each one of these berries has about 10 seeds inside of it. Pokeweed is spread by birds eating the berries and leaving the undamaged seeds in their droppings.

What sets pokeweed apart from most other weeds is that all parts of the plant are poisonous. The root is the most poisonous, the leaves and stems are intermediary (the level of toxin increases with maturity) and the berries have the least toxicity. However, there are reports of children being poisoned by the berries so, while less toxic, they’re still dangerous. The primary toxic compounds are phytolaccine, formic acid, tannin, and resin acid which cause gastrointestinal irritation but may also cause mutations and birth defects. Since these chemicals can be absorbed through the skin, it’s a good idea to not pull the plants with bare hands.

While this is a poisonous plant, in the South the young shoots are often eaten as a green that’s said to taste like either asparagus or spinach. There are also some who make pies or jelly from the berries. Personally, I would never eat this weed and am not recommending that anyone try it given its poisonous nature!

The other interesting thing about pokeweed is that it appears as an herbal remedy and is said to treat rheumatoid arthritis, tonsillitis, mumps, swollen glands, bronchitis and constipation. Once again, I’m not going to ingest this weed no matter what cures it promises to deliver.

Apart from the folklore about pokeweed, scientist have isolated one protein in it called pokeweed antiviral protein (PAP) which has shown anti-tumor effects on mice and antiviral effects on herpes and HIV in vitro and in animal studies. While this protein shows some possible medical uses, PAP is now made synthetically because the PAP extracted from pokeweed was often impure and contained the poisonous elements of this weed.

Common Pokeweed

Common Pokeweed

In the garden, pokeweed really isn’t a big problem unless you allow it to establish itself like I did. You can use a shovel and cut through the taproot of large plants to remove them; this will usually kill it. The one pokeweed I have right now is growing in the middle of an asparagus clump so I can’t dig it out. I figure I’ll keep pulling off new shoots as they develop. I also might cut the shoots and put a few drops of full-strength RoundUp into the hollow stems.

The best trick for controlling pokeweed is to keep up with the weed, pulling or cultivating it when you see it and not allowing the fruits to form. But given the fact that this weed grows all over the area, a few seeds will always end up in the garden and yard (thank you birds!). Pokeweed is something that’ll always be finding its way into the garden – I just need to keep a step ahead of it.

Advertisements

2 responses to “Weed du Jour – Common Pokeweed

  1. will the poisonous nature of the pokeweed contaminate the plants it grows around (i.e. your raspberries and asparagus)?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s