You know those moments where you think you know something–until suddenly you realize you don’t? Well this happened to me recently with periwinkle. I’ve seen this shrubby, large-flowered vine my entire life, but it wasn’t until I went to key it out that I realized I didn’t know its name. And when I finally came to periwinkle I couldn’t have been more surprised. This familiar plant is periwinkle? The periwinkle of literature, of blues and eyes and dresses? I always thought it would be some delicate British daisy; instead, it’s this coarse and common invasive!
The bigleaf periwinkle of real life is Vinca major, a dark-leaved vine with a milky, sticky sap. This invasive ground cover escaped from garden plantings and now is creeping across the U.S. In California you can see it in coastal areas, foothill woodlands, the Central Valley, and even in the desert. It forms dense mats, crowding out natives, and can resprout from bits of broken stem or root–a particular problem because it likes to grow on stream banks, where it regularly gets washed away in high water, taking root wherever the broken piece lands.
It climbs up brownstones and turns fences into bushy green hedges. It also smothers tree trunks and sometimes can carpet large stretches of ground. Wherever you find it, English ivy (Hedera helix) is a vigorous plant. It’s considered a serious invasive; in some places the carpet of ivy is so vast–and uninhabited by other species– that it’s called an “ivy desert”.
Ivy is best known for the strongly lobed, three-pointed leaves it sprouts when young. At first, I didn’t recognize the unlobed, “adult” leaves as the same plant–but they are. Older branches get thick and woody, and can have furrowed bark. Right now these mature vines are sprouting pom-pom-like flower buds; eventually these will give way to clusters of dark purple berries.
When English ivy grows on the ground, it only reaches a height of 8 inches or so as the single leaves reach toward the sky. But once it reaches something to climb, it can easily ascend 90 feet into the air, clinging to root-like structures that produce an adhesive glue-like goo. Some particularly robust plants can climb up to 300 feet! Individual plants have been found to be over 60 years old.
I once worked for a restoration company where one of our jobs was to clear ivy. One of the best ways to get rid of it where it had covered the ground was to chop into a leading edge with a hoe or shovel, and then roll the whole mass up like a rug. It was hard work but oddly satisfying at the same time.
This is one of the many unassuming plants that will be leaving souvenirs in your socks throughout the summer. With seed pods studded with hooked barbs, it catches easily on fabric and fur. Hedge parsley, or Torilis arvensis, is a mildly invasive species that has spread throughout much of the state (below 5,249 feet according to CalFlora, though such a precise number seems a tad arbitrary).
With tiny white flowers and only a few small leaves scattered along the stem, this calf-high plant is easily missed–though its burrs are more noticeable. Hedge parsley is in the large and diverse carrot family (or Apiaceae), landing on the untasty end of the spectrum that ranges from poison hemlock to culinary parsley.
It tastes great in salads, but fennel (Foeniculum vulgare) is an unfortunate weed in California. It grows avidly along roadsides and in other disturbed places. This plant grows up to ten feet tall, with feathery leaves and yellow umbrella-shaped umbels of flowers.
The leaves and the seeds have a distinctive licorice flavor, which is likely why the plant came to the Americas in the first place. It’s been used as a spice and a medicinal plant for centuries, and is thought to have escaped into the wild time after time.
Fennel is an invasive species, and takes over areas by forming dense stands where nothing else can grow. This isn’t just because the plants are so numerous that there is no room for any others. They also exude chemicals that actually prevent their competitors from growing!
Check out the above video for an musical animated interpretation of why fennel is a problem…
In ditches and along river banks, the berries are beginning to ripen. Great green mounds of shrubs – all leaves and thorny branches – are speckled with dark purple fruit. Younger berries are still green or red, and most bushes still have flowers on them as well.
This is the Himalayan blackberry (Rubus armeniacus), one of the most common berries around. It is also one of the only non-native invasive berries in the area. Though it’s delicious in pies, smoothies and endless other treats, this shrub can be a nasty problem for native habitats: I’ve seen it smother entire fields, leaving no space for native plants and the animals that depend on them. Usually you’ll see it in disturbed places and on poor soils. Despite the name, the bush originally came from western Europe and there is “no evidence” that it came from the Himalayas.
One nifty thing about this “fruit” is that it’s actually a bunch of small fruits – each little nub on the berry is called a “drupelet” in botany-speak.
This twining, white-flowered plant seems unobtrusive but it is also very distinct. When I first saw it, I knew that I had never seen it before – and it turns out that isn’t surprising. White ramping fumatory (Fumaria capreolata) is a mildly invasive species that is slowly spreading throughout the state. I first saw it in Sutro Forest, and since have seen it regularly in Bolinas. Right now it’s only found in a handful of counties up and down California. The only other states it is found in are New York and Florida.
Its diminutive white blossoms are tipped with a dark brownish red, and delicate three-parted leaves are spread sparsely along twining stems. Despite somewhat pea-like flowers, fumatory is actually in the Papaveraceae family – a diverse group that also hold both poppies and bleeding hearts!