Redbuds in bloom are a most welcome harbinger of spring. Their dense clusters of magenta flowers bloom early, providing splashes of color against a winter landscape of browns and grays. Is the name redbud really the best our ancestors could come up with for this beautiful tree? How could they call that color “red”? Even Wikipedia manages a more accurate “pink to purple.” Other sources are more specific, identifying the brilliant flora as bright pink, rosy pink, magenta, or reddish purple.
Cercis occidentalis is native to the arid western states. It is commonly known asWestern or California redbud, and sometimes Arizona redbud. Occidentem is Latin for “western sky” or “part of the sky in which the sun sets,” derived from the Latin verb occido – “go down, set.” The Occident is the longitudinal opposite of the Orient, and many species from China and other eastern regions are termed orientalis. Somewhere along the line, C. occidentalis acquired the second or synonymous binomial C. orbiculatum. Orbiculate translates naturally enough as round or circular in shape (in this case, in reference to the redbud's leaves). And if you are thinking now of Judas Tree as a common name, that belongs to the Eastern redbud. (Interestingly, the Latin name of the Eastern redbud is C. canadensis. And yes, you guessed it: canadensis is used in taxonomy to denote species indigenous to or strongly associated with Canada).
A hardy plant, the redbud is drought tolerant, sun-loving, and successful in a variety of soils. Typically, it prefers rather harsh environments with marginal, well-drained soils. It grows best in chaparral ecosystems below 4,000 feet in elevation, and prefers canyon walls and other steep slopes. It can also be found in gravely and rocky soils along streams above their flood zone. Western redbud tolerates some seasonal water and will grow in the bottom of ephemeral streambeds in little pockets, as well as on foothill benches, or tucked into crannies created by boulder outcroppings.
Western redbud is a popular landscape tree on the valley floor precisely because of its impressive beauty, which isn't restricted to eye-catching floral displays. The rounded, heart-shaped leaves are a silky combination of copper and green when they first emerge, darkening to various shades of green, gray-green, or blue-green. According to the USDA, the Western redbud's “autumn display of yellow turning to red and brown rival that of some eastern hardwoods.” This plant sets its fruit in the form of thin dry seed pods in autumn. Each pod contains about seven hard, bean-like seeds. As they ripen, the pods change in color from purple to russet brown. (On some redbuds, the mature pods hang on the branches into the next winter.) Once the redbud has shed itself of leaves and pods, the bare branches provide winter beauty as a silver-gray silhouette.
The straight, pliable, burgundy-colored young shoots of the California redbud were prized by native basket weavers. Designs were woven into baskets with redbud shoots, and a faint reddish dye derived from the bark was used to tint finished baskets. To ensure a reliable supply of this valued material, California tribes regularly burned hillsides in the fall, after the redbuds had shed their leaves. Prior to European settlement, the western Mono, foothill Yokuts, and Miwok Native Americans of the central and southern Sierra Nevada foothills set autumn fires at intervals of one to several years to encourage sprouting. Today's basket artists prune the shrubs to encourage the new growth.
This beautiful and hardy native shrub is nowhere near as dull and plodding as its common name implies. While the redbud makes year-round contributions to the landscape, the Arbor Day Foundation correctly notes that “the sheer springtime beauty of the redbud may be its greatest hold on the American spirit.”
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.
- Author: Kathy Keatley Garvey
if you hike a short distance up a meandering trail, you'll see a landscape of turrets, the work of solitary, ground-nesting digger bees, Anthophora bomboides standfordina.
The nests remind us tiny sandcastles. The female bees did that!
In the early spring you'll see the bees nectaring on wild radish and other flowers.
These digger bees are found along the sandy cliffs of beaches along the Pacific Coast, not just Bodega Head. They're sometimes called the “Stanford bumble bee digger” because its subspecies name, “stanfordiana,” refers to a 1904 Stanford University collection.
They are bumble bee mimics; they mimic the yellow-faced bumble bee, Bombus vosnesenskii.
It was Robbin Thorp (1933-2019), distinguished emeritus professor, UC Davis Department of Entomology and Nematology (ENT), who alerted us to them. He studied them at the Bodega Marine Reserve and loved to share his research.
So, on every trip to the Bodega Head, we scramble up the trail to see what the bees are doing. Of course, when they're overwintering, we don't see them at all, just the turrets.
Fast forward to today. On the ENT website, we posted a research story today that began 'Microbes found in the immature stages of a solitary bee that nests in sand cliffs along Pacific Coast beaches may be helping the bee defend itself from pathogens and protect it from cold stress, according to newly published research led by microbiologist Shawn Christensen of the Rachel Vannette Lab, UC Davis Department of Entomology and Nematology."
The research publication, “Symbiotic Bacteria and Fungi Proliferate in Diapause and May Enhance Overwintering Survival in a Solitary Bee,” appears in the current issue of the journal, International Society for Microbial Ecology (ISME), and is posted on the National Library of Science website.
“Contrary to what has previously been assumed and found in other systems, we found that dormant--also called diapausing--bees have more abundant symbiotic bacteria and fungi,” said Christensen, a doctoral candidate and the 2024 recipient of the Merton Love Ecology and Dissertation Award, an annual award that celebrates the university's most outstanding doctoral dissertation in the fields of ecology and evolutionary biology. He's scheduled to receive his doctorate this month.
The six-member research team, including colleagues from Cornell University, UC Riverside and the University of Arizona, also found “that the microbiome of this solitary bee is very consistent--the same taxa appear in most brood cells, in similar proportions,” said Christensen. “This is uncommon in solitary species, which normally have variable microbiomes due to lack of social transmission. We are still exploring this unique aspect!”
Vannette, associate professor and vice chair of the department and an international leader in microbial ecology, researches interactions between plants, insects and microbes. She is a principal investigator of a National Science Foundation grant that funded the project.
“Previous work on bee-microbe interactions has shown how gut bacteria benefit honey bees and other corbiculate social bees but these microbes are limited to social bees,” Vannette told us. “We wondered if solitary bees also associate with beneficial microbes and uncovered this previously undescribed partnership between bees, fungi and bacteria. This study opens up new questions in bee ecology and host-microbe interactions: how do solitary bees maintain specific associations with bacteria and fungi? What chemistry are Streptomyces using to suppress fungi? Does this association benefit bees? We think it is likely but ongoing work will examine these questions.”
“We are also thrilled to find this unique symbiosis in a bee species that has been well-studied by previous faculty at UC Davis, including RobbinThorp,” Vannette said. “UC Davis nematologist Harry Kaya, with graduate student Robin Giblin, also described Bursaphelenchus seani, a nematode that inhabits Anthophora bomboides. Our lab is also investigating links between the brood cell microbiome and the nematodes in this bee species.”
Other co-authors of the paper are
- Quinn McFrederick, assistant professor at UC Riverside who studies symbionts (pathogens, commensals, and mutualists) of wild and solitary bees
- Bryan Danforth, professor at Cornell University, who specializes in bee systematics and evolution
- Stephen Buchmann, pollination ecologist affiliated with the Departments of Entomology and of Ecology and Evolutionary Biology at the University of Arizona
- Sriram Srinivas, then a UC Davis undergraduate researcher in the Vannette lab
Check out Thorp's presentation on digger bees that he delivered at the “Proceedings of the Symposium on Biodiversity of Northwestern California” in October, 1991, in Santa Rosa.
Also check out the wonderfully done PBS Deep Look Video, This Bee Builds Sandcastles at the Beach.
Let's dig the digger bees.
- Author: Cynthia Zimmerman
“Well, I must endure the presence of a few caterpillars if I wish to become acquainted with the butterflies.” ? Antoine de Saint-Exupéry, The Little Prince
Monarch butterflies are more than beautiful; they contribute to the health of our planet by feeding on nectar and pollinating many types of wildflowers. They are also part of nature's food chain as an important source of food for birds, small animals and other insects. Monarchs are considered an ‘indicator species,' which means it's the canary in the coal mine. Its sensitivity to climate change, harmful chemicals and habitat destruction send a signal to address these conditions before there is more damage to the environment.
Due to the decline of monarch butterflies and their shrinking migratory paths in the United States, home gardeners are being encouraged to plant milkweed. Why milkweed? Monarchs cannot survive without milkweed. The females only lay their eggs on milkweed as they migrate. To grow and develop, the monarch caterpillars need milkweed plants.
Before you run to the nearest garden shop, nursery or box store garden center to help the plight of the monarch, there is something you should consider. There are many, many milkweeds on the market, some native and some tropical. The Monarch Joint Venture, Xerces Society and the U.S. Fish and Wildlife Service, all of which are dedicated to saving monarchs, all recommend only planting milkweed varieties that are native to your location.
Native milkweed in California typically flowers between late spring and the end of summer. Following seed dispersal, the above-ground portion of the plant dies back to the ground remaining dormant through the winter. In spring it re-emerges from the established root system.
Many of the varieties being sold are tropical milkweeds, which are not native to the U.S. and have foliage year-round when it grows where winters are mild and adequate moisture is available (in this circumstance, Fresno is considered mild). Research suggests that the tropical milkweed may encourage monarchs to lay eggs outside of their regular breeding season, disrupting their migratory cycle, and increasing the prevalence of monarch infection by the protozoan parasite Ophryocystis elektroscirrha, aka “OE.” If you have already planted a tropical milkweed in your garden, it is suggested that you cut it to the ground in fall when natives would be dying back. It should re-emerge in the spring. This would prevent the female from laying eggs at the wrong time in their migration.
The following California species should be your first choices when planting milkweed in Fresno, Clovis and surrounding areas:
- Butterflyweed (Asclepias tuberosa) – sometimes called Orange Milkweed. Large flat-topped clusters of yellow-orange or bright-orange flowers. Blooms May to September. Needs sunlight. Drought tolerant, dry or moist soil. 1-2 ft. tall.
- Antelope-horns Milkweed (Asclepias asperula) – Also known as Spider Milkweed. Pale greenish-yellow flowers, tinged with maroon. Blooms March to October. Needs sunlight, dry or moist soil. Medium water use. 1-2 ft. tall.
- Showy Milkweed (Asclepias speciosa) – Blooms May to September. Blue-green leaves and spherical clusters of rose-colored flowers. Shade tolerant, needs some sunlight. Medium water use. Moist soil. 1 ½-3 ft. tall but can reach 6 ft. under favorable conditions.
- California Milkweed (Asclepias californica) – Native to Central and Southern California. White-wooly plant and deep purple flowers. Blooms May to July. Drought tolerant, dry slopes. Maximum height 3 ft.
- Mexican Whorled Milkweed (Asclepias fascicularis) – aka Narrowleaf milkweed. Clusters of greenish-white flowers often tinged with purple. Blooms June to September. Needs sunlight. Drought tolerant. Dry to moist soil. 1-2 ½ ft. tall.
- Desert Milkweed (Asclepias erosa) – White to yellow flowers. Green to yellow stems. Blooms April to October. Best grown in desert conditions of sandy soil. Needs sunlight, dry soils. Not shade tolerant. 1-3 ft. tall.
Although milkweed does contain toxins, it is not usually a significant threat to animals or humans. Milkweed has a foul taste and is not likely to be consumed by pets or children in a quantity that would prove harmful. Still it is best to prevent accidental ingestion by teaching children to avoid contact with the plant and to wash their hands if they do touch it. If animal or human poisoning is suspected, call the poison control center or seek medical help.
For more information on milkweed and monarchs go to the following websites:
- Milkweed for Monarchs
- Native Milkweed by State
- Milkweed FAQ
- Monarch joint venture chart
- Journey North Tracking Migrations
- Pollinators – Monarch Butterfly
Originally written November 2019. Updated May 2024.
- Prepared by: Terry Lewis
Tasks
- Control weeds before they flower, produce seed and multiply.
- If citrus trees have scale, mites or thrips, spray with summer weight horticultural oil.
- Treat petunia, geranium and tomato plants with Bacillus thuringiensis (Bt) to control budworm and tomato hornworm.
- Deeply water fruit and nut trees. Ideally, mature fruit trees should be irrigated to a depth of 3 feet.
Pruning
- Pinch back new growth to improve plant shape and encourage bloom.
- If bush training fruit trees to a 5- to 6-foot bush, do not miss this pruning in June.
Fertilizing
- Do not fertilize cool-season lawns (fescues, bluegrass, perennial rye) during hot summer months.
- Avoid fertilizing herbs as too much fertilizer reduces flavor and fragrance.
Planting
- If your needs are such that you must plant now, remember to provide ample water and temporary shade.
- Fruits and vegetables: corn, parsnips, plant from seed.
Enjoy now
- Annuals and perennials: lisianthus (Eustoma), blanket flower (Gaillardia), gazania, globe amaranth (Gomphrena).
- Bulbs, corms, tubers: gladiolus, amaryllis (Hippeastrum).
- Trees, shrubs, vines: crape myrtle.
- Fruits and vegetables: boysenberries, eggplant, melons.
Things to ponder
- A small water feature, such as a recirculating fountain or a shallow pebble-filled bowl, provides drinking water for thirsty birds, butterflies and other garden wildlife. Regularly replenish the water and check for leaks.