[Note: Gray pine (Pinus sabiniana), buckeye (Aesculus californica), and blue oak (Quercus douglasii) are tree species that thrive in rugged local foothill woodland and chaparral habitat. Last edition, we covered the blue oak, and today the gray pine is featured. The final installment will explore the buckeye. All three species rely on adaptive strategies evolved over time allowing them to thrive in their challenging environment.]
But underneath that homely exterior lies a true gem. This tree's many common names testify to its importance: gray pine, California foothill pine, foothill pine, nut pine, bull pine, and ghost pine. Its pejorative historic name, digger pine, is no longer in use. The Maidu named it “towáni” and the Yana called it “c'ala'I.” Its scientific name derives from the English lawyer, naturalist, and writer on horticulture Joseph Sabine (1770 to 1837). Sabine had a lifelong interest in natural history and was an original fellow of the Linnean Society. It was Sabine who was responsible for sending David Douglas on specimen collecting trips, specifically to supply plants to the Royal Horticultural Society Gardens.
We are not certain of the lifespan of the gray pine, because older specimens were cut down by early settlers, but it is believed that these trees can live for over 200 years. When mature, they average from 40 to 80 feet tall. About 15 to 25 feet off the ground, gray pines develop two or more twisted stems that can grow at irregular angles to one another, resulting in a crown that appears open and ragged. Gray pine is self-pruning, and the remaining lowest branches will end up high above the understory. Where soils allow, gray pines can develop a deep taproot, but in hardpan soils their roots are spreading and shallow, and the bark thickens as the tree ages.
The female cones are the largest and heaviest in the entire pine family. They could be mistaken for a football lying amongst shed needles, as they can be up to one foot long, and when dry are dull orange/brown. A green cone can weigh over two pounds. That, and their sharp spines, warn one to be alert while treading under this tree!
Surviving Drought and Fire
In an evolutionary adaptation to the dry hot summers of a Mediterranean climate, the gray pine has thin, gray needles up to 12 inches long that help it deflect heat and retain water. Surprisingly, this species is not fire resistant. On the contrary, it is highly flammable: its needles contain ether extracts; its wood, bark, cones, and needle sheaths all contain pitch; and its trunk often is coated with resin that has dripped from wounds. Its fire survival strategy lies in two specific adaptations. First, large trees will better survive moderate-severity fires because the thickened bark of mature trees and the self-pruned trunks with high branching limbs are best able to avoid fatal scorching. Second, seed regeneration is actually favored post-fire. As noted by the USDA, fire creates a receptive “bare mineral soil seedbed, and heat scarification of the woody seed coat increases germination rates.”
Native American Uses
For California's native peoples, the gray pine was (and still is) a nutritional jackpot! Pine nuts are densely caloric, loaded with protein, easy to harvest, and store well for long periods. While many of California's pines provided food to native populations, the nuts of the gray pine were the most highly valued. They could be eaten raw, parched in baskets, and steamed in earth ovens. They were pounded into flour that was made into butter, soup, or bread; mixed with meal made from other dried seeds; and combined with dried salmon. In spring, green cones were roasted to yield a syrupy treat.
Crooked, ragged, and awkward as the gray pine may appear, its ability to thrive under environmental hardship, and its value to native peoples' survival make it an ecological and cultural champion. After all, handsome is as handsome does.
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.
[Note: Blue oak (Quercus douglasii), gray pine (Pinus sabiniana), and buckeye (Aesculus californica) are three species that thrive in rugged local foothill woodland and chaparral habitat. Today and in the following weeks, this series will look at these species and the adaptive strategies they have evolved over time to thrive in their challenging environment.]
Darwin, the product of a strictly codified class society beset by enormous economic inequalities, identified a major factor of evolution to be competition for finite resources. Those species that clambered to the top of the evolutionary heap benefitted from genetic mutations and / or adaptations that gave them a biological edge over their competitors.
Some species cooperate by sharing resources. For example, in Tortuguero, a tiny strip of beach along the northeastern shoulder of Costa Rica, four separate species of sea turtle lay their eggs each year. They migrate to the beach at different times, ranging from early March to October, and feed on different resources. Millions of turtles, and untold numbers of their babies, have shared the same tiny piece of real estate for eons.
Quercus douglasii also goes by a number of other common names, including white oak, mountain oak, mountain white oak, and iron oak. But it acquired its most familiar and descriptive common name from the same person from whom its Latin binomial (scientific name) is derived. In 1831 David Douglas, a Scottish botanist, christened it the blue oak for the bluish cast of its deeply lobed leaves. (A digression: Douglas, for whom the Douglas-fir and hundreds of other western plants are named, lived from 1799 to 1834. He made three trips to the American Northwest between 1823 and 1831, encountering the blue oak on his last trip while traveling from the Columbia River in Oregon to San Francisco. He died under curious circumstances, apparently after falling into a bull trap while climbing Mauna Kea in Hawai'i.)
Surviving Drought and Fire:
Adaptations to survive the long, hot, dry summers and sparse winter rains of our Mediterranean climate include thick leaves with a bluish-green color. According to the US Department of Agriculture (USDA), blue-gray-green leaf color reduces heat absorption. During severely hot and dry years, blue oaks will sometimes shed their leaves and go dormant to conserve energy, allowing these tough little oaks to survive temperatures above 100° F for several weeks at a time. Like many plants growing in marginal soils, blue oaks are slow growers, usually increasing only a few inches each year.
A further strategy to survive drought and fire conditions is the blue oak's extensive root system, which allows it to grow through cracks in rocks to depths of 80 feet in order to reach ground water, helping it to survive in fire-prone and arid regions (Blue Planet Biomes).
Although blue oaks can tolerate fast-burning grass fires, they have less success in surviving hotter brush fires, according to University of California Department of Agriculture and Natural Resources (UCANR). If a tree does survive a fire event, it can reproduce both through seeds and by sprouting from burnt stumps. Blue oaks can produce sprouts after a low- to moderate-severity surface fire, and younger trees have the edge on older trees for fire survival odds. On younger trees, the light-colored bark (hence “white oak”) is thick and helps reduce fire damage, the USDA notes, whereas the bark of mature blue oaks is thin and will flake off as the trees age, making older blue oaks less insulated against fire. After a fire, blue oaks can also re-establish from acorns that have dropped from surviving parent trees and/or been dispersed by animals, among other possibilities.
Native American Uses:
All parts of the blue oak were woven deeply into the culture and survival of California's native peoples. It was one of more than a dozen oak species whose acorns contributed a major source of dietary nutrients and calories. Because of their superior flavor, blue oak acorns were among the most commonly gathered.
A Plant Guide published by the Natural Resources Conservation Service (NRCS) provides an exhaustive list of the ways California Native Americans used blue oak wood, bark, and acorns, including as “medicine, dyes, utensils, games, toys, and construction materials.” Locally, the Maidu used oak shoots to frame cradleboards and oak posts to construct shelter, and the Yana used an oak paddle in cooking. Traps for birds were baited with acorns, and split acorns became dice for gambling.
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.
We in Northern California are fortunate to live in a climate that enables us to garden all year. Our moderate temperatures enable many vegetables to grow through the winter, and at most lower altitudes, frosts are rarely severe enough to kill resistant plants and vegetables.
Sunlight warms the soil, and retained heat minimizes the effects of below-freezing temperatures. Sunlight warms the plants themselves, and provides the light energy that enables the complex chemical process of photosynthesis.
The problem of sunlight for winter gardeners is that there is simply less of it. Everyone knows this, but too often we don't consider it carefully when planning or planting a winter garden. In summer, one must often think about protecting plants from harsh, direct sunlight.
In winter, plants must be placed where they will be exposed to the maximum light available. In winter, not only are the days shorter by several hours, but the sunlight strikes the earth at an indirect angle, thus transmitting less energy for heat and photosynthesis.
Compared to other seasons, the winter sun rises later, describes a much lower arc through the sky, reaching barely a quarter of the way to the zenith, and sets much earlier. A winter garden, whether a square mile or a square yard, receives only about one-third of the sunlight it gets in mid-summer, and only half of what it gets in mid-fall and mid-spring.
For the same reasons, shadows from obstructions near the garden such as trees and shrubs or buildings and fences, matter more in winter than in other seasons because they are much longer, shading a larger area for more hours of the day.
A plant which basks in full, radiant sunshine during the bright quarter of the year (May, June, and July) may well be in the chilly shade during the dark quarter (November, December, and January).
Finally, to top off this list of light-deprivation horrors,heavy cloud cover, not uncommon from October through March, reduces available sunlight even further, by a factor of over 50 percent.
This “light assessment” will involve a bit of thought and time, and maybe some rudimentary diagramming, but it will pay off in better plant location, much more vigorous plants, and more success in gardening through the winter.
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.
Cold, windy, rainy weather provides ideal conditions for the development of Citrus blast, a disease that affects many varieties of citrus grown in Butte County, including oranges, grapefruits, lemons and mandarins. Citrus blast is characterized by individual leaves that rapidly wilt, dry up, and die on the tree. The leaf stem turns brown and a brown lesion will form on the twig where the infected leaf is attached. The leaf blades may drop or remain stuck on the tree but the dead leaf stem (petiole) often remains attached to the twig. On young vigorous shoots the lesion at the base of an infected leaf may grow around the shoot, girdling the twig and causing twig dieback. On damaged twigs a reddish-brown crust will form over the diseased spot.
The most effective control of citrus blast is achieved by spraying a protective fixed copper material before the first heavy rain in November. Sprays applied in the fall will help protect leaves and shoots from winter storms, but must be applied before blast injury occurs. In years with heavy rainfall, a second spraying in January is appropriate to protect tissues from storms in February and March. These sprays will also help protect fruit from fungal infections that cause fruit loss. Cultural practices that harden off growth in the fall before the cold, rainy weather arrives will help reduce the severity of blast damage. Avoid over-fertilizing that encourages trees to add tender late-season new growth. The last nitrogen fertilization on citrus should be applied no later than late May. Using these chemical and cultural controls should help reduce blast damage to citrus trees.
Winter has finally arrived in the north state! Winter temperatures can pose a threat to the fruit and foliage of citrus, as well as other succulents, tender perennials, tropical and subtropical plants.
The most common type of frost in California is referred to as radiation frost. Radiation frost occurs on cold nights when the air is clear and still. Soil, buildings, plants, and other objects at the earth's surface act as a heat reservoir by absorbing heat during the day. Heat is lost, or radiated, from the earth's surface into the atmosphere and plants are damaged when enough heat is lost from this reservoir to lower the temperature at the surface to below critical temperatures. Greater damage occurs with colder temperatures or a longer duration of cold. Temperatures can drop more rapidly when the air is very dry and the dewpoint is low. If the dewpoint is very low a freeze can occur without the formation of dew and frost. This condition is known as a “black frost.”.
Avoid planting frost-sensitive trees in the lowest areas of the yard or garden, as cold air tends to flow downhill and can accumulate in such depressions. Trees planted near structures or walls, particularly those with southwest exposure that absorb and retain reflected heat during the day, may be damaged less during periods of frost because that heat is released during the night. Fertilize and prune during the spring and early summer so that new foliage will have enough time to mature before the onset of cold weather. Bare, moist soil stores more heat during the day and radiates more heat during the night, so rake away mulch, ground cover, weeds and leaves from around the tree during cold weather.
Monitor weather forecasts and take note of how low temperatures will go, and for how long. When the weatherman warns of frost, there are several precautions you can take to protect your plants.
- Identify cold spots in your landscape by monitoring with thermometers
- Identify plants at risk: citrus, succulents, tender perennials, tropical & subtropical plants
- Have supplies ready: either sheets or blankets with stakes or a framework to hold covers off foliage, or frost cloth (which can lie directly on plant foliage); lights; wraps for trunks; thermometers.
- Wrap trunks of tender trees, using towels, blankets, rags or pipe insulation.
- Move potted plants to warmer spots next to the house or under a patio cover.
- Water plants and trees. Dry plants are more susceptible to damage and moist soil retains heat better than dry soil.
- Cover plants just before sunset to capture and hold in as much heat as possible. Remove sheets/blankets daily if it's sunny, to allow soil to absorb heat during the day.
- Add heat by hanging a 100-watt lamp designed for outdoors in the interior of the tree, or use a holiday string of outdoor lights (not LED lights, since they don't give off heat).
If the larger branches of a tree or plant sustain frost damage, don't prune away damaged wood or remove the plant too soon. Wait several months in order to assess the extent of the damage and allow time for possible recovery during warm weather. As new foliage begins to grow, frost-killed twigs and branches will be apparent and can be pruned at that time. Postpone heavy pruning until the following year to allow trees to regrow to the point where damaged wood can be clearly determined.
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.
