Why are wine bottles tall and narrow? That distinctive shape contributes to the happy marriage between cork and a bottle made tall enough to lie on its side so the wine can “breathe” through the cork as it matures. Lying on its side while stored in cool, dry cellars ensures that the liquid within the bottle will marinate the cork end just enough to keep it from drying out and crumbling.
What do wine, wax, and wrinkles have to do with local trees? In 1904, a cork oak grove was planted in Lower Bidwell Park near the Nature Center on East 8th Street. The grove was located within a 29-acre tract of land that John Bidwell donated in 1888 to the newly created State Board of Forestry for use as a woody plant nursery and demonstration plantation.
Cuttings and young plants were collected from all over the globe for the project, including species of willow, mulberry, linden, maple, oak, catalpa, pine, and eucalyptus. The ensuing planting spree in the 1890s included Sequoia gigantica, a tract of Italian cypress (these trees gave rise to the name “Cedar” Grove), and a large plot of Scots pine. Of those late-19th century conifer plantings, only the cypress remain: the Sequoia were decimated by a freak freeze in 1932, and bark beetles took all but a few of the pines.
The species can reach about 66 feet in height, but is usually smaller than that in its native habitat. There are two notable exceptions: In Portugal, the Sobreiro Monumental (Monumental Cork Oak), is 234 years old and 52 feet tall, with a trunk so large in circumference that it takes up to five people with outstretched arms to encircle it. It is listed as a National Monument, and cited in the Guinness Book of Records as the largest and oldest cork oak in the world. Closer to home, a Quercus suber in Napa is registered as a California Big Tree. It is 89 feet tall, with a trunk circumference of 20 feet, and a crown spread of 81 feet.
The acorns of the cork oak have a distinctive fringed cap, smooth chestnut skin, and characteristic green mark at the bottom, and the tree's shiny, deep green, loosely-lobed leaves are attractive. But its bark is the cork oak's claim to fame. Almost ghostly pale in color, the bark is deeply furrowed and springy, and provides an ecologically sustainable cash crop. The thick, insulating bark also makes it possible for the tree to survive fires, after which it regrows branches to fill out the canopy.
Modern uses aside, the method of harvesting the bark from the cork oak dates back to the Middle Ages, using an axe that has barely changed in all that time. Virgin (or “male”) cork is cut for the first time from trees about 25 years old. After that, the bark is harvested every 9 to 12 years. Trees can live over 200 years, and one harvest of bark from a single tree can produce enough to cork 4,000 bottles.
In the harvesting process, the bark is peeled from the tree by hand, using only an axe to strip the bark from around the tree. Absolutely no machinery is employed. It can take up to five people to harvest the bark of each tree. Because expertise and finesse is required to peel off the bark without damaging the trunk's cambium layer, harvesters train for about 8 years.
Our cork oaks in Lower Bidwell park were also harvested periodically; scars from a stripping performed in 1940 and again more recently are visible even now.
In addition to providing cork bark, cork oak groves in Portugal and Spain support another form of agriculture: their acorns provide sustenance to sheep, cattle, and especially hogs. A superior type of ham with a distinctive sought-after flavor is obtained from the Iberian pigs that feed on the fallen acorns.
Our local cork grove in Lower Bidwell Park provides a window into the past by hearkening back to the ancient farming traditions of the Mediterranean countries, and is a living legacy to John Bidwell's quest to, as local naturalist Rex Burress elegantly stated, grow plants “far from their native origins but brought together to mingle in a new habitat.” Best of all, in my opinion, is our cork oak grove's genetic bond to those trees that make a crucial contribution to good wine.
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.
In honor of Arbor Day, which was October 21 (we are a little behind, you know why), UC Master Gardener Melody Kendall has these remarks about her favorite trees in Fuller Park.
Arbor Day, which falls on October 21 this year, is a perfect day for a stroll in Fuller Park. This beautiful Napa park is the city's arboretum with over 60 outstanding trees, many marked with signs that provide useful information about each tree. For me, walking the park today is vastly different from my earlier strolls.
When I was growing up here in Napa in the 1950s, the weekend treat was a visit to Fuller Park for an afternoon of fun. Back then, all I was interested in was conquering the spiral slide. Over the years I returned sporadically. In 2014, when I became UC Master Gardener, I finally realized what an amazing place Fuller Park is.
Fuller Park is on the National Register of Historic Places and was originally known as Campbell's Grove. Acquired by the City of Napa in 1905, it was turned into a city park called Oak Street Park. The name was changed to Fuller Park in 1919 to honor C.H. “Jack” Fuller, the Napa mayor involved in the acquisition of the property.
The UC Master Gardeners of Napa County are offering guided tree walks in Fuller Park from June through October. When I joined the tree-walk team, all I knew about the different trees was which ones were evergreens and which were not. That's not much information for conducting a guided tree walk. To learn more, I have since spent many happy hours wandering through the park and familiarizing myself with its remarkable collection of trees.
My favorite tree is the Bunya Bunya, a native of Queensland, Australia. What's not to like about a tree that can reach a height of 140 feet (the recorded high is 147 feet), with a trunk like a dinosaur leg and with cones bigger than a Thanksgiving turkey? Plus, the edible inch-long seeds hidden in those cones have long been a food source for the native peoples of Australia and are still considered a delicacy.
Another exceptional tree is the graceful dawn redwood (Metasequoia glyptostroboides). It is thesole remaining species of its genus. This tree has cinnamon-colored bark and light green, lacy foliage. Believed to be extinct until, in 1941, it was found in a remote region of North China, this tree can grow in standing water. My favorite little factoid about the dawn redwood is that it is a deciduous conifer. While most conifers stay green all winter, this tree's leaves turn a burnt orange and drop. The tree is bare all winter.
Another fascinating tree is the cork oak (Quercus suber). Its knobby, dark-gray bark is a lucrative commodity. Native to the Western Mediterranean and North Africa, most cork oak forests are in Portugal and Spain. The bark is the primary source of cork for wine bottle stoppers, cork flooring, gaskets and the cores of cricket balls.
Once they reach maturity, cork oaks are harvested every nine years. Harvesting the bark doesn't harm the tree; the bark regrows. The year of harvest is marked on the trunk, so each tree is harvested at the right time. Unlike many other oak trees, cork oak is an evergreen and does not drop its leaves. Touching the bark is a very tactile experience.
Among the 60 tree species at Fuller Park, it is hard to find a tree that isn't interesting in some manner. There is a group of Chinese hackberry trees (Celtis sinensis) that are native to Eastern Asia. These trees are members of the cannabis family, but with no THC, which is the psychoactive compound.
The bald cypress (Taxodium distichum) is more often found in the swamps of Florida and in Louisiana bayous with the roots forming knees. Every part of the English yew (Taxus baccata) is poisonous except for the small cup-like structure that holds the berry. The poisonous alkaloid found in this tree contains some chemicals effective in combating lung and prostate cancers and in treating advanced breast cancer.
The English elm (Ulmus procera) was used for water pipes by the Romans because it is not susceptible to rot. The wood of the Northern red oak (Quercus rubra) is so porous that if you blow smoke into one end, it would come out the other end.
The City of Napa and the UC Master Gardeners of Napa County have created a virtual guided tree walk, with posted signs on 40 different trees. Each sign has the common name and Latin name of the tree plus a QR (quick-response) code that you can scan if you have the appropriate app on your smartphone. Scanning the code sends you to the Master Gardeners' web site with information for the tree you scanned. Some brief facts will be displayed with an optional audio link for further information
Celebrate Arbor Day be joining UC Master Gardeners of Napa County on a free guided tree walk on Saturday, October 21, at Fuller Park. Meet at 10 a.m. on the corner of Jefferson and Oak Streets. The City of Napa is an official “Tree City USA,” recognized by the National Arbor Day Foundation. Napa maintains this honor through tree preservation, care and reforestation programs such as the Annual Arbor Day tree planting
Workshop: The UC Master Gardeners of Napa County will hold a workshop on “Toxic and Carnivorous Plants and Mushroom Kits” on Saturday, October 28, from 9:30 a.m. to 11:30 a.m., at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Foxglove. Lily-of-the-valley. Wisteria. These common plants and others are toxic. Who knew? Sundew. Venus flytrap. Pitcher plant. They're carnivorous. While we would not touch a mushroom in the garden, growing edible fungi from kits is easy and neither toxic nor carnivorous. Explore the fascinating properties that plants have to protect them. Online registration (credit card only);
Mail-in registration (check only or drop off cash payment).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.