Sunny yellow flowers, toothed leaves, and a seed head that simply begs to be blown are all characteristic of the weed commonly known as dandelion.
The word dandelion, which means lion’s tooth, actually refers to several different plants in the sunflower family. Native to Europe and Asia, dandelions have been following humanity across the globe, taking advantage of soil disturbed by agriculture, fires, and construction. This makes them a ruderal species. Ruderal species are the first plants to colonize disturbed land.
Bane of lawns everywhere, the common dandelion (Taraxacum officinale) was brought to North America in the 1600s to be used as both food and medicine. The species name officinale refers to an early English word meaning medicinal.
Cousin to lettuce and chicory, dandelions are easy to recognize, with their low-growing (basal) rosette of toothed leaves and bright yellow or orange composite flowers. Composite flowers are actually made up of several florets, clustered together. Dandelion florets reflect ultraviolet light, which attracts many beneficial insects, looking for nectar and pollen. Surprisingly, dandelions do not need to be pollinated to set seed. Instead, seeds are produced asexually, in a process called apomixis. As a result, all offspring are identical to the parent plant. Besides the floral stem, dandelions are acaulescent, which means they appear to not have any structural stems.
Dandelion flowers open each morning and then close each night, in a behavior called nyctinasty. Each plant can produce up to ten floral stems. The cuplike structure seen at the base of each dandelion floret is called a calyculus. Once the flower has matured, it will begin to dry out. After the dried petals and stamens fall off, specialized leaves, called bracts, curve backwards, exposing the seed ball. Each stem produces a single seed ball. These seed balls are commonly called blowballs or clocks. The seeds we see are actually a special type of fruit, called a cypsela. The feathery bristles that act like a sail are called pappi (pappus, singular). The hollow flower stem contains a bitter latex used to defend against herbivores.
Latex is used to make rubber. While most of the latex used to make rubber today comes from the rubber tree (Hevea brasiliensis), you can make your own rubber from dandelion latex! You can make an elastic band simply by coating your finger with dandelion latex, allowing it to dry, and then rolling the latex off your finger. Voilà! You can also make a bouncing ball or waterproof fabric out of dandelion latex. [Did you know that a man named Charles Macintosh figured out how to smear latex between two pieces of fabric to make waterproof fabric? That’s why raincoats are often called macintoshes!] When dandelion latex dries, it stays sticky until it cures. Curing latex involves applying heat and sulfur. The curing process removes the stickiness. Dandelion rubber is stiff in cold temperatures and supple when it is warm. Only Russian dandelions make a latex that is strong enough to be used commercially. [I just learned that one company is researching the use of Russian dandelion latex to make automobile tires!]
Dandelions as food
All parts of the dandelion plant are edible, but you may want to harvest the newest leaves to avoid some of the plant’s bitterness. Eaten the same way as spinach, dandelion greens are packed with good nutrition, including high levels of vitamins A, B, C, and D, according to the University of Maryland Medical Center. Dandelions also contain a lot of iron, calcium, potassium, and zinc. Young dandelion roots can be peeled and eaten. They are said to taste like turnips, but I haven’t tried them yet. The roots can also be roasted and used as a coffee substitute. The flowers are also edible. They can be sautéed in oil with a little garlic and they can be used to make dandelion wine.
Dandelions as medicine
Traditionally, dandelion has been used to treat infections, digestive problems, as a mild laxative, and to stimulate the appetite. Dandelion leaf tea was said to “purify the blood” and the milky latex was used as both mosquito repellent and wart remover, though I couldn’t find any scientific proof to back up any of these claims. According to WebMD, no research has demonstrated any verifiable medicinal use of dandelion, though it does contain chemicals that decrease swelling and increase urine production.
These herbaceous perennials have taproots that are strong enough to counteract compacted soil. Hell, they can break through concrete! While dandelion roots are typically only 6 to 18 inches deep, some specimens go 10 to 15 feet deep! Dandelion plants can live for up to 10 years and reach 20 inches in diameter.
I used to try to eliminate dandelions from my lawn, despite my love for their bright yellow flowers and the irresistible seed heads. I finally decided to try putting the plants to work for me in my heavy clay soil. While mulching and growing green manures and cover crops has significantly reduced soil compaction on my property, I have a theory about dandelion taproots. It goes something like this: Since dandelion taproots are strong enough to break asphalt, I allow them to grow, regularly removing the greens (for salads and as a treat for my chickens), before flowers emerge. My theory is that the dandelion taproots will dig down into my compacted soil, bringing microorganisms with them, to create healthier soil. Even if it doesn’t work, I still get pretty flowers and edible greens. Maybe I’ll even try making dandelion wine, one of these days. If my theory is wrong and I end up with a severe problem with dandelions and other, similarly growing weeds, I make have to resort to other control measures.
If you really must get rid of the dandelions in your lawn, it will take consistent effort on your part. As you already know, those seeds can blow in on the wind from miles away. This battle never ends. While herbicides will certainly kill individual dandelions, those same chemicals can be toxic to other living things, such as us, and our pets. Maintaining a healthy lawn and removing plants as soon as they are seen is the best control method. Cutting off young plants at ground level, a practice called grubbing, is effective only if you are diligent. Crabgrass preemergent herbicides advertised as effective against dandelions do not prevent seeds from germinating.
Love ‘em or hate ‘em, dandelions have been around for 30 million years, and they are here to stay.
You may as well make the most out of these common weeds.
There’s the toe tappin’, git yer yee-haw on sort of bluegrass, and then there’s one of the most common California weeds: annual bluegrass.
Annual bluegrass (Poa annua) is a cool season annual or biennial that appears in the Bay Area with the first rains. This weed is a member of the grass family.
Annual bluegrass identification
Annual bluegrass starts out looking like many lawn grass varieties, Kentucky bluegrass, in particular, except that it has shallower roots, seeds more rapidly, and it is a lighter shade of green. To the untrained eye, grasses are grasses. A yellowish to dark green blade emerges, a couple more blades show up, and then a flowering stalk comes out of the center, hosting a flower cluster that spreads this problem far and wide. To identify annual bluegrass, you will need to take a closer look at the blade. The tip is said to look like the bow of a boat. The mid-blade may have a crinkly section. And the collar, where the blade meets the sheath (or stem), has a slightly pointed, jagged tip. Annual bluegrass grows low to the ground, spreading in clumps that can be 3 to 12 inches tall. The root system is fibrous and you may even see roots emerging from the lower portion of the aboveground stem. Flowers may be seen December through July. Flower heads are egg-shaped or triangular, and can be bright green or purplish.
Why do you care?
At first glance, this weed may look like an acceptable addition to your lawn. It’s a grass. It’s green. It grows like crazy. So, why would we consider this particular grass a weed? Well, first, it turns brown and dies back as soon as the top of the soil gets dry, leaving ugly, dead patches in your lawn. Those patches then erode or create homes for other weeds. In the garden, this weed robs your edibles of water and nutrients needed to stay healthy and produce an abundant harvest.
Annual bluegrass control
Watering your lawn deeply and infrequently will make life more difficult for annual bluegrass. It will also make your lawn healthier and more drought tolerant. Also, maintaining your lawn at a height of 3 or 4 inches will shade out this weed. Individual clumps can be dug out as soon as they are seen. I feed them to my chickens, but you can add them to the compost pile, as long as they haven’t gone to seed. Heavy infestations can be treated with pre-emergence herbicides in late summer or early fall, if you use that sort of thing. [I don’t.]
If annual bluegrass is seen in the garden, pull it out before it has a chance to go to seed and spread. You can also lay 6 to 8 sheets of wet newspaper over unplanted areas of the garden and then cover the paper with 2 to 3 inches of organic mulch, such as pine needles, straw, or aged compost. The wet newspaper acts like a weed barrier and the mulch feeds the soil while interfering with weed seed development.
Devil’s apple is a poisonous weed from Africa.
Called Devil’s apple because of its toxic yellow fruit, Solanum linnaeanum made an appearance under my almond tree. When I went to pull it out, I discovered its substantial thorns.
Considered an invasive in Australia, Devil’s apple has been getting a lot of press lately. Dramatic statements declare that Solanum linnaeanum can cure skin cancer. And I could not find a single piece of scientific evidence to back up those claims. Hmmm. Yet another snake oil salesman… Why do we tolerate all those untruths?
The truth about Devil’s apple is interesting enough on its own, so let’s learn what we can.
Devil’s apple is a member of the nightshade family, along with potatoes, tomatoes, and eggplants. These shrubs can reach 6 feet in height, and those spines can be 1/2 an inch long. I sure wouldn’t want to fall into one of those bushes!
Also known as apple of Sodom, Afghan thistle, and Dead Sea apple, this weed invades pastures, agricultural fields, roadsides, and now, my yard.
The yellow berries start out as a star-shaped, 5-petaled purple flower, the way most nightshades do, but then they start looking more like a small apple, hence the name. The fruit changes from white or green to bright yellow and it contains toxic alkaloids. DO NOT EAT THEM!!!
Devil’s apple is also host to the Malaysian Fruit Fly, which earns it a listing in the California Code of Regulations, as part of the state’s emergency eradication program. Other than that reference, I have not been able to find any mention of the plant in California, so I have submitted an information request to local Master Gardeners and UC Davis to see if this is a new weed in the Bay Area. I’ll keep you posted.
For the time being, if you see one of these in your garden or landscape, dig it out.
You can grow a surprising amount of food in your own yard. Ask me how!