Sacred datura (Datura wrightii). A vigorous herbaceous perennial that grows to 5 feet tall
and wide. The striking flowers, which bloom from April to October, are sweetly fragrant white
trumpets up to 8 inches long, often tinted purple. The fruit is spiny and conspicuous. This is
a flowering and poisonous ornamental plant of the nightshade family (Solanaceae), growing abundantly in Southern California. Members of the Datura genus are sub-classified as “deliriant” hallucinogens, known for causing considerable disturbances in cognition, visual and auditory perception, and a multitude of psychological facets relating to memory and attention. (Credit – Krzysztof Ziarnek via Wikimedia Commons)
Great Valley gumplant (Grindelia camporum). A hardy, gangly perennial in the daisy family (Asteraceae). It’s native to California and Baja California and is often found in chaparral and
woodland habitats. It grows up to 6 feet high with erect, branching stems lined with stiff, wavy-edged, serrated leaves and a single large flower head atop the branches. The flower head fills with an oozing white exudate, especially during the early stages of blooming. It is a traditional Native American medicinal plant, used by the Indigenous peoples of California, and a major
pollinator attractant. (Credit – H. Zell via Wikimedia Commons)
Baja fairy duster (Calliandra californica). This evergreen, woody shrub is native to Baja
California, Mexico and the Southwestern United States. In the spring and early summer, it
attracts hummingbirds and butterflies with clusters of bright-pink, fluffy flowers and red
stamens. The shrub grows up to 6 feet tall, with bipinnate leaves described as “fern-like.” (Credit – Krzysztof Ziarnek via Wikimedia Commons)
Woolly blue curls (Trichostema lanatum). A many-branched evergreen shrub that is native to arid coastal regions of California. It grows to 5 feet tall, with narrow, pointed green leaves, and dense clusters of smooth-petaled blue flowers with the stems and calyces covered in woolly hairs of blue, pink or white. Growers have developed several cultivars that serve as ornamental
plants and also attract hummingbirds and bumblebees. (Credit – The Marmot via
Wikimedia Commons)
Golden fleece (Ericameria arborescens). This flowering shrub in the daisy plant family
(Asteraceae) is native to California and Oregon, where it is a resident of chaparral communities
and open woodlands. This is a resinous, hairy shrub that can exceed 10 feet in height. Its many
erect branches are covered in bright green, very thin, needlelike to lance-shaped leaves. Atop each stem is a cluster of many bright golden flowers, each a rounded bunch of disc florets about 2 inches wide. This plant is drought-tolerant once established, excellent for bees and butterflies, and adapted to ecosystems prone to wildfire. (Credit – George Williams via Wikimedia Commons)
Show Caption
1 of 5
Sacred datura (Datura wrightii). A vigorous herbaceous perennial that grows to 5 feet tall
and wide. The striking flowers, which bloom from April to October, are sweetly fragrant white
trumpets up to 8 inches long, often tinted purple. The fruit is spiny and conspicuous. This is
a flowering and poisonous ornamental plant of the nightshade family (Solanaceae), growing abundantly in Southern California. Members of the Datura genus are sub-classified as “deliriant” hallucinogens, known for causing considerable disturbances in cognition, visual and auditory perception, and a multitude of psychological facets relating to memory and attention. (Credit – Krzysztof Ziarnek via Wikimedia Commons)
Expand
Biodiversity is a very large subject that is well worth everyone’s time and attention. Today’s column provides a brief overview of the topic and then focuses on home gardening.
Before we dig into this topic, review today’s plant gallery, which relates to our transition to California native plants.
Today’s image gallery
Today’s photos feature a few of California’s uncommon plants selected from Wikimedia Commons, rather than examples from my garden. These are not rare specimens, but they suggest the range of some 6,500 plant species native to the Golden State. The California Native Plant Society’s Calscape website (calscape.org) offers data for over 8,500 cultivars, which includes natural varieties.
Biodiversity overview
Biodiversity has been defined broadly as the variability of life on Earth. More specifically, it refers to species diversity and species richness. It is a natural occurrence among all living organisms, and varies with climate regions, geologic elevations and marine and terrestrial environments.
Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or decrease or disappear in a specific area. Over the ages, natural events have led to large and sudden drops in biodiversity.
Human activities have led to an ongoing biodiversity loss. Human activities include habitat destruction, such as farming, deforestation and other forms of monoculture. Other human activities also contribute to the loss of diversity: air and water pollution (including nutrient pollution), overexploitation, collecting medicinal plants, introducing non-native invasive species and climate change.
Biodiversity with garden plants
While developing a residential landscape, homeowners often prioritize monoculture (lawns), and gardeners appreciate a wide variety of exotic plants (invasives). These practices may drive local native species to extinction by competing effectively, displacing preferred environments or hybridizing with related native species.
Ecologist Doug Tallamy has noted that “we have replaced the native plants necessary to fuel food webs with non-native ornamentals valued only for their aesthetics.”
Lawns and alien invasions can cause extensive changes in the garden’s structure, composition and global distribution of the animal and plant life of a particular region or habitat. This leads to the homogenization of a garden’s fauna and flora, and the loss of biodiversity.
The response to this problem includes design policies, guided by science, to encourage the use of native plants in our gardens and communities.
California gardeners can pursue this constructive, ecological design by visiting public gardens featuring California native plants.
Visit native plant gardens
The California Native Plant Society’s quarterly magazine, Flora, recommends 10 public gardens that showcase California native plants. This section provides edited versions of Flora’s descriptions of six public gardens nearest to the Monterey Bay area, with driving distances from Santa Cruz. Public gardens generally require an admission price to support operations.
John Muir National Historic Site Garden (north of Concord — 2 hours). Naturalist John Muir, typically associated with Yosemite National Park, also managed a large fruit orchard. The CNPS East Bay Chapter transformed Muir’s home property into an “all-California native garden.” For info, browse nps.gov/jomu.
Pacific Grove Museum of Natural History (north of Monterey — 1 hour). This is one of California’s oldest and most well-established destinations to explore the state’s native flora. The garden features three spaces that reflect the area’s important local ecosystems: coastal scrub, chaparral and oak woodland. Browse pgmuseum.org for more.
Santa Barbara Botanic Garden (Santa Barbara — 4 hours, 30 minutes). This 76-acre classic is the quintessence of a community-based, biodiversity showcase. The garden offers more than six miles of paths through habitats featuring 1,000 species of California native plants from over 11 different dedicated ecosystems. The garden will celebrate its 100th anniversary in 2026. For info and required reservations, visit sbbotanicgarden.org.
Santa Ynez Chumash Museum and Cultural Center (north of Santa Barbara – 4 hours). This 3.5-acre garden opened in May, featuring 11,000 plants in 100 native plant species with traditional uses to the locally historic band of Chumash people. This small but inspirational native garden space broadens one’s understanding and appreciation of native plants as agents of significant cultural heritage and a life-sustaining force for local indigenous Chumash people. Browse sychumashmuseum.org.
Tilden Regional Parks Botanic Garden (Berkeley — 2 hours). This 10-acre park, a majestic setting in the Berkeley Hills, celebrated its 75th anniversary this year. Its plants represent 10 regions of California. Its western flank — the “Canyon Section” — comprises most of the garden’s regional native plant species. For more information, visit nativeplants.org.
Tule River Parkway (north of Bakersfield — 4 hours). Located in the Central Valley town of Porterville, this park offers 32 discrete planting spaces organized by theme. The spaces have been “adopted” by local sponsors and tended by CNPS volunteers. Browse tuleriverparkwayassociation.org.
In addition to Flora magazine’s recommendations, at least two other public gardens include native plant sections well worth visiting.
UC Berkeley Botanical Garden (Berkeley — 2 hours). This garden is home to one of the largest species collections of California native plants in the world, including more than 200 plants on the California Native Plant Society’s list of rare and endangered species. About a third of California’s native plants are endemic to California, meaning that they can only be found in the state. Visit botanicalgarden.berkeley.edu/collections/california for information on the California collection.
UC Santa Cruz Arboretum and Botanic Garden (Santa Cruz — less than 1 hour). The California collection includes many native plants naturally occurring on the site. Most noteworthy are the ponderosa pines, probably the most maritime and at the lowest elevation of the entire North American range of the species. In addition, coast redwoods, Douglas firs, coast live oaks, California bays, willows, cottonwoods, madrones and buckeyes are there, along with rolling meadows of native bunchgrasses. For information on the California collection, visit arboretum.ucsc.edu/about/garden-collections/california-gardens.
Advance your gardening knowledge
To dig deeper into today’s topic, search Wikipedia for “biodiversity,” “biodiversity loss” and “effects of climate change on plant diversity.”
To focus on biodiversity in the garden, read entomologist Doug Tallamy’s brief article, “We Know Enough to Act,” which is included in the current issue of the CNPS’s magazine, Flora, and available online at tinyurl.com/5evzenwy.
Search the CNPS’s website resources, which “imagine a California in which water-thirsty lawns are replaced by life-giving native plants, creating a thriving, connected network of natural habitat and California beauty.”
This week in the garden
Review your landscape to consider limiting a lawn monoculture and replacing exotic plants with California’s native plants.
Enjoy your garden!
Tom Karwin is a past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a past president and lifetime member of the Monterey Bay Area Cactus and Succulent Society, a Lifetime UC Master Gardener (certified 1999-2009), past board member of the Santa Cruz Hostel Society and a current member with the Pacific Horticultural Society and other garden-related societies. To review the archive of recent On Gardening columns, visit santacruzsentinel.com and search “Karwin.” Go to ongardening.com to review columns from 2012-2020 (and eventually) from the following years. Please send comments or questions by email to gardening@karwin.com.
Comments are closed.