It's the scary season for this invasive plant

This cluster of pokeweed berries shows how they look at all stages of ripeness. Unripe ones resemble tiny green pumpkins, but the berries fill out, resembling blueberries, when ripe. (Photos: Kathy Morrison)

Ghosts, haunted houses, bats and other scary images are in season. But do you know what really makes me shudder? Seeing ripe pokeweed berries at child height.

Usually pokeweed berries grow in grapelike clusters, but sometimes they appear in clumps like this.

Those dark purple berries are toxic to humans, dogs, livestock and other mammals. The birds who eat and carry them around, conveniently reseeding the plant, somehow are immune to the poison. Gardeners, you may be growing this plant for a lot of reasons -- it IS pretty, with its white flowers and red stems -- but if it's near where children or dogs walk or play, please reconsider.

American pokeweed ( Phytolacca americana ) is an invasive plant with a long history. It's a native of  eastern and southeastern states that has spread over the years to parts of California, including the Central Valley, according to the UC Integrated Pest Management program, which just last week updated its public information page on pokeweed.

"Pokeweed is found in riparian areas, oak woodlands, forest edges, fence rows, forest openings, pastures, under power lines, disturbed areas, vineyards, orchards, cultivated fields, parks, and ornamental landscape," the IPM pokeweed page notes. You'll notice that a lot of those sites are hangouts for birds.

The plant has some uses: The berries' juice make wonderful dye, apparently, and also has been used for ink. Historically the leaves were considered edible; one of its alternate names is "poke salad."

But  UC IPM is unequivocal in its warning against consuming any part of this plant:

"Although sometimes eaten, the entire plant is poisonous and should be considered with extreme caution. The leaves and stems of young pokeweed plants can be ingested only after repeated blanching; without proper preparation, pokeweed can cause a variety of symptoms, including death in rare cases."

A single pokeweed plant can produce up to 7,000 seeds annually.

Pokeweed is invasive and a survivor. Its seeds remain viable for up to 50 years, according to the UC IPM page. Once established, it has a long taproot and doesn't require regular water. It dies back after the first frost, then re-sprouts in spring.

Say you've discovered one of these plants in your garden and want to cut it down. First of all, don't put any of it in your compost bin or the green waste container. And wear gloves, since the ripe berries burst easily and stain fingers. Put a large trash bag over the stem with the ripe berries, and then cut the stem so the berries fall into the bag, not on the ground. When you have cut off all the berry clusters, tie the bag and put it in the trash bin. Then dig out the rest of the plant with a shovel, going after the taproot, and discard that, too.

In the spring keep an eye out for new sprouts. As with any invasive weed, the best organic advice is "Just keep digging."

Chemical controls are possible, UC IPM notes, but that's mostly for agricultural eradication; if you're curious, the instructions can be found at the page linked above.

And if a child eats the berries -- stains around the mouth will be a giveaway -- contact Poison Control immediately. There's a poison control for pets , too.