Most trees have thick bark. The bark insulates the living tissue from weather and protects it from insects. Have you ever wondered why manzanita has bark so thin that it peels in midsummer? Kate Marianchild did, and she set out to find the answers to a multitude of questions about what makes manzanitas so special.
Marianchild’s Zoom presentation in January to the Santa Clara Valley chapter of the California Native Plant Society is archived on YouTube – search “The Amazing Manzanita and All Her Relations.”
Manzanita bark is wafer thin. When the bark peels away in midsummer, the trunk and branches are green underneath, containing chloroplasts. So, manzanitas can take advantage of the long days of summer by photosynthesizing even more sugars through the exposed trunk and branches as well as the leaves. The rest of the year, light can penetrate the thin layer of bark. The annual peeling, along with the smoothness of the bark, keeps lichens, moss and fungi from attaching themselves to it. Bitter tannins in the bark also deter insects and are responsible for the red-brown color.
If you do see lichens and moss on a manzanita, Marianchild said, you will find dead wood underneath. Gray striping on the bark is dead wood that, she speculated, the plant sacrificed in extreme drought conditions. Although the bark resists fungal colonies, the roots rely on mycorrhizae – fungi that help plant roots harvest water and nutrients from the soil – more than most plants.
Leaves and flowers of manzanitas are also adapted to drought. The hard, leathery, wax-coated leaves keep their edges turned toward the sun, minimizing water loss from their surfaces. The flower buds form many months in advance so that when conditions are right, they can burst into bloom on a dime.
Because manzanita flowers bloom during the winter rainy season, their downward-opening urn shape and waxy coating protect pollen from being washed away in a rainstorm. Queen bumblebees hibernate all winter and because they can fly in cold weather, emerge in sync with the bloom to collect pollen. To release the pollen, a bumblebee “buzzes” each flower until the pollen is released onto her abdomen, then moves on to collect more at the next flower. Each time she moves to a new flower, some of the collected pollen is transferred to that flower. In this dance between bee and flower, each flower gets pollinated, and the bee gets enough pollen to eat and to store in the cells where she lays her eggs.
Other insects also feed on the nectar that manzanitas provide during the winter, but some of these are what Marianchild called “beeloaders”: nectar thieves that cut holes in the flower, taking nectar without providing pollination services. Year-round Anna’s hummingbirds as well as migrants rely on manzanita nectar, and more than 50 species of moths drink the nectar of common manzanita.
Planting a manzanita
To help this ecological story unfold in your garden, plant a manzanita. California has nearly 100 species and subspecies, and a wealth of garden-tolerant cultivars, all drought-tolerant. Here are a few:
• Dr. Hurd manzanita is a reliable large shrub, 10-12 feet tall and wide, that can be pruned to show off the red-brown bark and serve as an eye-catching focal point.
• Howard McMinn manzanita is probably the most-planted variety in gardens and public places because it tolerates average garden conditions so well. It tolerates pruning and is easily kept at 5-6 feet high and wide, but it can eventually be 8-feet-by-15-feet.
• Pajaro manzanita and Sunset manzanita both have coppery new growth and are also medium size, 5-8 feet high and wide. Pajaro has pink flowers; Sunset has white flowers.
• Point Reyes manzanita is a neat groundcover with pink flowers that is usually 6-12 inches high and 4-8 feet wide.
Tanya Kucak gardens organically. Email her at [email protected]