Thanks to the contributions of two energetic people who know plants, chavezpark.org is publishing a complete botanical inventory of the park. Jutta Burger PhD is Lead Scientist for the California Invasive Plant Council, and Bob Huttar is a certified arborist and a consulting field biologist specializing in botany generally and rare plants in particular. Together they are photographing and identifying everything that grows in the park, both common and scientific names. They’ve done the scientific heavy lifting. I’m adding some background blog-talk. We’re publishing the results in a series, with a new installment every Friday.
This Friday’s featured flora focuses on some of the park’s many bloomers. We can’t do them all in one post, there’s too many. In no particular order, but starting very small, we have the Common Chickweed with its tiny white flower, the Henbit with small purple blossoms, the interesting California Burclover, and the selective Brass Buttons. We conclude this week with the fragrant Victorian Box Tree and the profusely flowering Tansy Ragwort, two plants with pretty covers but toxic interiors. More blooms next week.
The chickweed (Stellaria media) may have earned that name because people used to grow it as food for their chickens. It’s also good people food, fresh in salads or cooked; it has a high iron content. Several uses are found in folk medicine. It’s one of the seven herbs consumed ritually in the Japanese springtime festival Nanakusa-no-sekku on January 7.
Henbit (Lamium amplexicaule) doesn’t seem to have a specific utility for feeding chickens, but it is human-edible raw or cooked, like the chickweed, above. Its purple flowers, shown here in the bud, can cover whole meadows. It tends to flower early in the season, forming an important resource for bees before other plants come online.
The California Burclover (Medicago polymorpha) looks ordinary but has an unusual quality. It forms a symbiotic relationship with a nitrogen-fixing bacteria, so that it improves the soil where it grows. Its tiny yellow flowers attract pollinators. The plant is edible and is a frequent summer vegetable in China. Despite the common name, it’s native to the Mediterranean area. It has spread over most of California and is rated as “invasive.”
Brass Buttons (Cotula coronopifolia) prefers soils that many other plants avoid, namely brackish wetlands. It can tolerate a lot of salt. Where those conditions obtain, it can take over and become locally invasive. Elsewhere it’s not an issue. There doesn’t seem to be any commercial nursery interest in this plant.
Victorian Box Tree
The Victorian Box Tree (Pittosporum undulatum) is a fast-growing Australian native tree or bush that is classified as invasive in California and many other areas. It has sweetly fragrant flowers and sticky-sweet fruits. The fruits contain a toxic chemical, saponin, but this substance resists human stomach acids and tends to pass through the body without causing harm. Fish are not so lucky; traditional peoples have thrown large quantities of the fruits into lakes or streams, paralyzing or killing the fish. CalFlora rates it as having MAJOR toxicity.
Few plants drive wedges among people like the Tansy Ragwort (Senecio jacobaea aka Jacobaea vulgaris). Several bushes grow brightly and cheerfully in the southwest extension of the park, behind the boat shop buildings. Originally from Eurasia, the plant now grows almost everywhere in the world with rain and cool nights. In the U.K., where it has been studied extensively, the plant provides a home and food source to at least 77 insect species, 30 of which live on ragwort exclusively, plus another 117 species that rely on ragwort in their migrations. Ten of the insect species that depend on ragwort are rare or threatened. Among them is the cinnabar moth, a species that is rapidly declining. The ragwort is able to support so many different insects because it is a prodigious producer of pollen and nectar. A single plant may produce more than 2,000 flowers over a six-month growing period. A British study rated it as the top producer of nectar sugar.
That’s the good news. The bad news is that the plant’s leaves and flowers contain many different kinds of alkaloids, which give the leaves an unpleasant smell and are poisonous to cattle, horses, and humans. These poisons affect the liver and can damage DNA. The cinnabar moth’s larvae consume the plant in order to absorb the poisons and make themselves bad-tasting to predators, a survival strategy. The plant’s nectar also contains these alkaloids, and bees that visit the plant pass the poison into their honey. Cows who eat the plant may pass the poison into their milk. Small amounts can be dangerous because the toxins accumulate in the body.
Given these qualities, ecologists and others concerned with maintaining biodiversity, particularly in the face of threatened insect populations, find themselves supporting the plant’s right to exist. Ranchers who raise cattle and horses, on the other hand, want it gone. The latter have, on the whole prevailed with the regulators. Ragwort is listed as a noxious weed in the Republic of Ireland and as an injurious weed in the United Kingdom. It’s listed as noxious by the California Department of Food and Agriculture and by the California Invasive Plant Council, and by Washington and Oregon state agencies. The plant is not grown commercially and is not available in nurseries or as a seed. Various biological strategies have been mounted against it and have reduced its population. Nevertheless, ragwort remains far from extinction. Few people who admire its generous blooms are aware of the turmoil that lurks beneath this pretty face.