24 karat gold. It is the measure designated for pure gold. But where does it come from?
Ironically, it is derived from the seeds of a carob tree (Ceratonia siliqua), an arboreal species that you could hardly call glittery or glitzy. Carob tree flowers are drab and barely noticeable, and since the carob is an evergreen species, its leaves do not change color.
As noted by Max Adams, author of “Trees of Life” (Princeton University Press, 2021), “Twenty-four carob seeds came to be the standard weight of the Roman gold coin known as the ‘solidus’ – and hence 24-carobs (or carats) became a measure of 100 percent pure gold and of proverbial quality.”
Such arcane information is scattered throughout Adams’ richly illustrated tome. It has the classic look of a coffee table book, but it will arouse your curiosity when you open it at random — to the point where you will want to read it cover to cover for its lively descriptions of 80 trees.
What distinguishes illustrations in “Trees of Life” is their variety, including photographs of trees in their habitat, Van Gogh paintings of mulberry, olive, pear, almond, and peach trees, and artistic botanical drawings, some of them rendered hundreds of years ago and yet as vivid, if not more so, than any smartphone image could be.
I had no idea that the camphor tree (Cinnamomum comphora) could live for 3,000 years, as it does in its native Japan. After a rain, no tree is more stunning than a camphor. Its luminescent foliage glistens when wet and its furrowed bark turns a distinctive jet black after a rain. Whether wet or dry, it’s foliage emits a strong camphor scent when crushed. At one time, this tree was widely planted in our area but is less commonly seen nowadays because of its mature size.
Over the last several decades at least, the trend in urban tree planting has been toward smaller trees that are less expensive to maintain than classic big trees such as oaks, sycamores, and elms. Still, there is nothing more breathtaking than large mature trees on both sides of a street. Examples include the American elms on Indian Hill Boulevard in the city of Claremont, or the sycamores on Cantura Street in Studio City, or the deodar cedars on White Oak Avenue in Granada Hills, or the jacarandas on Stansbury Avenue in Sherman Oaks.
The cork in our wine bottles comes from an oak species (Quercus suber) that is highly drought-tolerant and grows well in Southern California. In commercial cork oak forests – found in Spain, Portugal, Algeria, and Morocco — trees are first stripped of their outer corky bark when reach twenty-five years of age. Such a procedure would kill most trees, which is what happens, for example, when a crepe myrtle is carelessly whipped around its base by a string trimmer or weed eater until a ring of encircling bark is completely removed from the trunk. When this happens, the flow of water and minerals up the trunk (through the xylem) to the branches and leaves and the flow of sugars down the trunk (through the phloem) to the roots is interrupted and the tree dies. Yet somehow the cork oak is impervious to removal of xylem and phloem for the period of time required until its outer bark begins to grow again. Mature cork oaks have their bark harvested every seven to ten years and may live for two and a half centuries.
Although the word “paper” is derived from “papyrus,” a plant grown in moist soil from ancient Egypt to contemporary Los Angeles and whose pith was made into crude strips upon which scribes could write, paper as we know it was invented by the Chinese 2,000 years ago. The fibers macerated into pulp — in the process by which paper is manufactured until today — came from the bark of the paper mulberry (Broussonetia papyrifera), a tree that grows easily in our part of the world, and whose fuzzy foliage is delightful to touch. Not only is paper associated with mulberry trees but silk, too, as it has been made for 4,000 years, also in China, out of the strands of cocoons woven by silkworms (actually caterpillars of grey-winged moths) after gorging themselves on mulberry foliage.
If you are curious about the Bodhi tree under which Buddha, according to legend, sat for 40 days before receiving enlightenment (or Bodhi), you can easily grow one in Los Angeles. Appropriately dubbed Ficus religiosa, and thus referred to as the sacred fig, the Bodhi tree is distinguished by its heart-shaped leaf with a distinctive elongated tip, reminiscent of a stingray’s whip-like tail.
A section of “Trees of Life” is devoted to fruit trees. “Most fruit trees are bushy,” Adams writes. “They put their energy into the fruit rather than trying to outgrow their competitors. Fruit cultivators like to keep their trees small too, to make harvesting and pruning easier. The mango, in its native India and Malaysia, is a huge exception, growing to more than 115 feet.” Unlike most fruit trees whose fruit-bearing may be confined to a few decades at most, the mango has the capacity to produce a crop for more than 300 years.
You can sprout mango seedlings from supermarket fruit. You can either place the entire pit horizontally one inch below the soil surface, preferably in a container, or scrub and rinse off the fibers covering the seed, split open the seed coat and remove the embryo nestled inside. Sometimes an embryo is polyembryonic, meaning that when you plant it several shoots will emerge. Generally speaking, polyembryonic seedlings will grow into trees with fruit that resembles the mother plant whereas trees from monoembryonic seeds will have fruit of an unpredictable quality. Be patient. It may take three weeks for shoots to start poking through. Carefully monitor soil moisture. Mango (Mangifera indica) seeds do not like to sit in overly moist soil but they should not be allowed to dry out either. I have seen mango trees growing in Granada Hills where they were planted in sunny garden spots that, by proximity to block walls or other structures, were afforded some cold protection. This is vital since the mango’s tropical origins prohibit its exposure to freezing temperatures for more than a brief period of time, although a mature tree will have greater cold resistance than a young one.
You might not think of the San Fernando Valley as walnut growing territory but at one time it was known for that. I quote from the May 14, 1920, issue of the Van Nuys News: “Keen competition for the new packing house to be erected in the San Fernando Valley by its walnut growers has sprung up between Burbank, Van Nuys, and Lankershim.” ‘Placentia’ is probably the best variety of walnut to grow in the Valley. You can still see ‘Placentia’ trees, planted in vast orchards around 100 years ago, in certain neighborhoods from Woodland Hills to Encino to the city of Walnut itself in the east San Gabriel Valley.
Walnuts have been praised for their power at holding back the onset of dementia. It is said that just a handful of walnuts each day contributes significantly to cerebral acuity. The fact that the walnut resembles the human brain is consistent with the Doctrine of Signatures, a medieval belief system that held that the form of a fruit, nut, or vegetable is indicative of the body part it was divinely designed to protect from illness. You can order a ‘Placentia’ walnut tree from Bay Laurel Nursery in Atascadero (baylaurelnursery.com).
Tip of the Week: Pine nuts are one tree crop you can find throughout the Los Angeles area, wherever pine trees are planted. Pine nuts are not nuts in the usual sense – such as almonds, walnuts, pistachios, and pecans — with a fleshy pericarp, but are naked seeds found in pine cones. Harvest pine cones before they open and place them in a mildly warm oven with the door ajar. Turn the cones as they heat up until they begin to open. Then peel away the scales of the cones, extracting the seeds from the base of each scale at the cone center. Put seeds back in the oven until they crack, revealing the soft pine nuts inside their husks. Once nuts are free from their husks, you can roast them a bit more or just eat them as is. Pine nuts are found inside every pine cone but you will want to focus on the bigger cones. Italian stone pine (Pinus pinea) is one pine tree species that is encountered here and there, recognizable by the flat top of its dome. Its pine nuts are large and tasty.
Please send questions, comments, and photos to Joshua@perfectplants.com