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SYMMETRY GROUP

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Ilex Castaneifolia Buy


Ilex castaneifolia is a form of Ilex x keohneana, thought to be of French origin, and due to its strong apical dominance it produces a medium to large tree with a distinctively pyramidal shaped crown.




ilex castaneifolia buy



Grande arbusto o talora alberetto a sviluppo vigoroso e di forma piramidale, Ilex castaneifolia (Chestnut-Leaf Holly nei paesi anglosassoni) è una varietà femminile di agrifoglio vincitore di un Award of Garden Merit nel 2002. Le foglie, piuttosto grandi, sono denticolate (ma non pungenti) ai margini, verde brillante, spesse e coriacee, la cui forma ricorda quelle di un castagno, da cui il nome specifico. In autunno produce (sul legno vecchio), gruppi di bacche rosso brillante piuttosto numerosi, che spiccano fra le foglie. La fioritura, molto meno evidente, avviene in primavera, con mazzetti di fiori bianco-crema all'ascella delle foglie. Piuttosto esuberante, si adatta a molti terreni, a patto che abbiano un buon drenaggio, e si presta sia come arbusto isolato, che per formare siepi (a crescita non velocissima!!)


Because of its unique lineage, and the rarity of wild-collected Q. castaneifolia in the US (see below), I collected acorns in 2016. Oaks are anemophilous (wind-pollinated) species that generally rely on fertilization from genetically different individuals of the same species for successful seed development. But there is some evidence that oaks have the ability for self-pollination on a limited basis (Yacine and Bouras, 1997). Of the 24 seeds collected, 12 germinated and the resultant seedlings so far appear to be true-to-type, despite extensive nearby plantings of US native and exotic species including Quercus macranthera (Caucasian oak), which is reported to hybridize with Q. castaneifolia. Despite promising initial results, verification to identity will have to wait until the seedlings mature. If anything, they can serve as understock to graft scions from the original tree, which would preserve the exact genetic lineage.


Records of this species in cultivation in the United States are few. Some of the largest are two 1938 trees (239-38*A and D) at the Arnold Arboretum of Harvard University, which came from the Mount Mashuk Forest Garden Experimental Station in Pyatigorsk, Russia (Northern Caucasus), which is outside of the species natural range. The larger of the two (239-38*D) stands 22.33 m (73.3 ft) tall, has a spread of 18.3 m (60 ft), and a DBH of 98.6 cm (38.8 in). A query of the most current inventory (2014) of the members of the Plant Collections Network multisite Quercus group indicated 19 living accessions of Quercus castaneifolia in nine gardens. Of these, 16 are of garden or nursery origin, two are from wild collections, and one is actually a hybrid: Q. castaneifolia Q. cerris. Interestingly, the two wild plants are 1994 accessions growing at the UC Davis Arboretum and originally came from Dr. Ahmad Mossadegh, Professor of Silviculture at the University of Tehran. He collected seeds from the Loveh Region, near Gorgan, Iran at an elevation of 830 m (2723 ft). This source locality, similar to that of the Longwood specimen, indicates that all of the known wild-sourced material in cultivation in the US comes from a similar place in the eastern extent of the species range. In addition to growing in the institutions mentioned above, chestnut-leaf oak is also at the Bartlett Tree Research Arboretum (Charlotte, NC), Denver Botanic Garden, Cornell Botanic Gardens (Ithaca, NY), and Morton Arboretum (Lisle, IL). Its ability to grow in such diverse places suggests a tolerance to extremes of heat and cold (USDA Hardiness Zones 5 to 9), as well as drought and a range of soil types. It is worth experimenting growing the tree in colder and drier regions where the palette of available landscape trees is limited.


Chestnut-leaf oak is perhaps the most widely cultivated tree in the Lankaran Region. We immediately encountered extensive plantings used as windbreaks amongst the vast agricultural expanses that dominate the Caspian Lowlands. Street trees were also common, which thrived despite compaction from surrounding sidewalks and streets, late-summer heat and drought, pollution from vehicle exhaust and general neglect. PCC members are again planning an autumn 2018 trip again to southern Azerbaijan to make collections of this and other important, under-represented species. Hopefully, our success in capturing the northwesternmost extent of its range will increase the presence of wild-origin Q. castaneifolia at public gardens across the US,


Here is a prediction. By 2040 (if not sooner), the largest oak in California will no longer be a California native Quercus lobata. Instead, it will be one of the Quercus castaneifolia growing at the Shields Oak Grove in Davis. The tallest of these trees is well over 100 feet in height, in about 50 years. In 15 years of observation, the trees do not seem to be slowing their growth. Given that the largest Q. lobata in the state are quite old, and almost invariably in decline, it's virtually inevitable that the largest will be surpassed by the remarkably vigorous imports.


The Q. castaneifolia love the growing conditions in Davis, and, remarkably, showed no change in vigor and health status when the large lawns in the Shields Grove were removed and watering vastly decreased. The continued vigor shows clearly that the trees are tapped into underground moisture supplies, which tend to be abundant in the Davis area, and are mixed into coarse and deep alluvial soil characteristic of the Davis area.


Interestingly, and typically, European oak experts who have seen the trees claim they are not true Q. castaneifolia, but instead hybrids between Q. castaneifolia and Q. cerris. Since the seed for the Shields trees originally came from Kew Gardens in England, and, sure enough, there are numerous Q. cerris at Kew, close to the large Q. castaneifolia, which was grown from acorns originally collected in Iran in the 1830's. Properly marked, the huge trees in the Shields Grove are Quercus castaneifolia x cerris.


Regardless of exact parentage, the Davis trees are regular producers of medium to large acorns. Hundreds or thousands of seedlings from the Shields nominal Q. castaneifolia have been propagated by California nurseries, and the offspring are invariably hybridized. Some of these offspring are marcessant. Some of the offspring are very upright in growth habit, while others are quite pendulous. Virtually all offspring are resistant to powdery mildew. On good quality sites, the seedling are among the fastest growing oaks that exist, commonly growing 4 to 6 feet each year.


So, yes, like many oaks, you can grow superior specimens derived from these trees in California. The problem with the seedlings is the marked variation in traits and performance from individual to individual. The Q. castaneifolia planted at Apple Park appear to be carefully selected offspring of the Davis trees, but, despite clearly careful selection, there is still a wide variation from tree to tree. Some individuals display an enhanced susceptibility to Phythophthera, but this could also be a response to root defects in the form of girdled or circled roots started early in the life of the tree.


Among oaks from other parts of the world historically planted in California, Q. ilex is clearly the tree that has been used the most, and results have been less than ideal, for a variety of reasons. Some of the key problems include intense aphids and sooty mold in many locations, a destructive root system when used in proximity to infrastructure, unpleasantly heavy shade for urban locations, near-agricultural levels of acorn production, major stunting of planted trees due to girdling and circling roots in nursery production, and, finally, invasiveness.


Quercus ilex has been a sad tale for the California landscape industry. After decades of scattered use in California, Q. ilex became heavily planted in rapidly urbanizing post-war California from the 1950's to the 1980's. One prominent set of such urban Q. ilex grew in the California Avenue commercial area in Palo Alto.


These trees became the center of a civic firestorm in 2009, when the 50 or so Q, ilex, planted in the 1980's, were suddenly removed by the city of Palo Alto, with virtually no public process. This act was part of what eventually led to the retirement of both the head of public works and also the head arborist. City officials had relied on the agreement of a small number of business owners on the street who hated the trees for several of the reasons cited above.


But these were highly visible, and even beloved, business district trees, and the public outrage was immediate. A replacement tree plan was pulled together, and new trees installed within months. Most of these trees have performed well, and, of course, did not feature Q. ilex. The story of California Avenue, which can be found detailed in newspaper stories from the time, is truly a cautionary tale for those not yet convinced to leave Q. ilex out of California.


Almost certainly, the trait that served as the "last straw" for the California Q. ilex was acorn drop. A bit of study into the history of Q. ilex in the Mediterranean shows that it was a critical component in the dehasa production system, which specialized in the fattening of the famous Iberian swine. Quercus ilex was a primary provider of acorns on the dehasa, with particularly productive strains likely selected for 1,000 human generations, all choosing to propagate the Q. ilex which produced the most abundant and largest acorns.


Humans turned Q. ilex into an agricultural tree species. Then, people who did not understand the genesis of the tree, and its characteristics, decided to plant the tree along the sidewalks of a busy commercial district. And, of course, all these acorns dropped between Thanksgiving and Christmas, right into the heart of the Holiday shopping season. Clearly, not an ideal scenario, and clearly not the right oak for widespread urban planting in California. 041b061a72


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