Whether it’s the puffy, white seed balls of the dandelion or the creeping, succulent stems of purslane, weeds are a constant challenge to gardeners everywhere.

But it turns out, one person’s weed can be another’s prized greenery.

A great number of the plants we consider weeds are not only edible, but many are considered superfoods, according to Douglas G. Kent, a professor at the Center for Regenerative Studies at Cal Poly Pomona and author of the book “Foraging Southern California: 118 Nutritious, Tasty, and Abundant Foods.”

Kent has been foraging for and growing the plants that gardeners would just as soon pluck and throw away in their compost bin for decades, and he is an advocate for the ways those things can be cooked and used.

He gets excited as he discusses how weeds and humans have a long and shared history. Many of these plants were things that our early hominid ancestors adapted to eating, he said, and there’s also a reason you can find these plants all over the globe.

“It was a co-evolution,” he said. “Our system was evolving to them; their system of seed distribution was evolving to us. And so we went together. We traveled the world.”

Ground rules

Before you forage for weeds, Kent recommends following some safety tips. Consume only those plants you can positively identify, and wash foraged plants with water warmer than the leaves. Warmer water expels potential toxins from the plant, while cooler water can cause the toxins to be pulled in.

Kent also recommends starting in the place that’s most familiar to you — your own garden.

“And once you’ve nailed your own garden, then work on your neighbor’s garden, and then go out into the wilderness,” he said.

In his book, Kent encourages would-be foragers to also consider the legal risk before they go out and collect weeds. He urges not to enter private land without permission. Places such as commercial properties and state colleges sometimes do not allow collection of plants. Kent recommends checking the restrictions for those places online before heading out.

On the hunt

Want to know what weeds Kent finds in Southern California? From wild mustards to curly dock, here are some common ones.

Black mustard >> This wild mustard is very common in Southern California. Its leaves, flowers, fruits and seeds are edible, Kent said, and high in fiber as well as vitamins A, C and K. The mustard can be eaten raw, added to salads or made into pesto, but because the leaves have a strong flavor, they’re best added to flavors that will dull their own.

Cheeseweed >> This plant prefers dry, disturbed soils; look for it at trailheads and on the sunny sides of buildings. Kent said the leaves can be eaten raw or cooked. The flowers and immature green fruits can also be eaten. The plants are rich in pectin, which Kent said is good for the skin.

Curly Dock >> The leaves can be eaten raw, boiled, steamed or roasted, but it’s best harvested midwinter to midspring. If harvested later in the summer or fall, the leaves may need to be seared to get rid of bitterness and acids.

Dandelion >> Kent called this common weed “the belle of the ball of herbology,” and noted the roots, stalks, leaves, flowers and seeds can be eaten.

Goosefoot >> This relative of spinach can be found all over Southern California but is most common within 125 miles of the coast. Leaves could be eaten raw or cooked, and the seeds are also edible. It’s high in vitamins A, D and C, according to Kent.

London rocket >> This plant is abundant across Southern California, from the coasts to the mountains. Up close, it looks similar to arugula and has flavors reminiscent both of that plant and of mustard — and it makes sense, since it is a part of the family Brassicaceae, which includes mustards, arugula and broccoli. Leaves of this plant can be eaten raw or cooked. It’s best to pick the lower leaves, and younger plants taste better than older ones.

Purslane >> This is another weed found near people, and it tends to be more common in more populated areas. It pops up in areas where the dirt has been disturbed and in areas of “incidental irrigation,” according to Kent’s book. This weed has a tart and lemony kick and is used in all sorts of recipes. Kent adds it to salads with other greens such as nasturtiums and mustard, puts it into juices and on top of eggs, and cooks it by itself.

Grow your own

Want to bring a piece of the wild weedy world home? It’s not only possible to forage many of the weeds common in Southern California but to grow them.

Kent grows his own weeds at his home and is excited about the purslane that has spread out over a section of gravel in his yard.

“Everybody that comes, I tell them to stay on the tracks,” he said with a smile. “Don’t ruin my crop!”

Seed companies such as Baker Creek Heirloom Seeds sell some of these plants, according to Baker Creek horticulturist Randel Agrella. The company stocks an improved version of purslane with slightly larger leaves and several varieties of dandelion.

Agrella said potential weed gardeners can also obtain seeds by collecting them as they forage, but they should do their research before they start to grow seeds from those things.

He recommends not only reading up on the plants but observing the kinds of conditions they’re growing in.

For example, a plant growing only at the edge of pavement could be there because of the water runoff it gets, which may be a sign it needs more than what it would get out in the open.

Agrella suggests that gardeners pay attention to when things are sprouting. If a particular kind of plant sprouts in February, it’s a good idea to plant the seeds from it just before February instead of July.

“After they’ve identified some plants that they like and they know of an area where maybe the plants come back year after year, go there and just observe,” he said.