![]() As a result of such high rates of hybridization and introgression, genetic data often does not differentiate between two clearly morphologically distinct species, but rather by different populations. ![]() Frequent hybridization and high levels of introgression have caused different species in the same populations to share up to 50% of their genetic information. Most notably, hybridization has led to the creation of large populations of hybrids, copious amounts of introgression, and even the evolution of new species. Recent systematic studies appear to confirm the high tendency of Quercus species to hybridize as a result of a combination of the aforementioned factors.įrequent hybridization has brought about a number of consequences to oak populations around the world. Ecological stresses, especially near habitat margins, can also cause a breakdown of mate recognition as well as a reduction of male function (pollen quantity and quality) in one parent species. Botanists have often described white oaks as having weak internal barriers to hybridization, that is to say, because they are wind pollinated, oaks often do not discriminate against being pollinated by another species in the same section ( Quercus), thus resulting in fertile hybrid offspring. Yet not all plant groups exhibit hybridization. Hybridization is considered fairly common, if not widespread, in the plant world (certainly much more so than in animal taxa). Interspecific hybridization is quite common among oaks, especially in the white oak group (subgenus Quercus, section Quercus see List of Quercus species). The genus Cyclobalanopsis, here treated as a distinct genus following the Flora of China, is often included within Quercus as a distinct subgenus. Hybrids are common in oaks but usually only between species within the same section no verified inter-section hybrids are known, except between species of sections Quercus and Mesobalanus, where several occur. Leaves typically have sharp lobe tips, with spiny bristles at the lobe. Styles long, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Lobatae (synonym Erythrobalanus), the red oaks of North America, Central America and northern South America. Leaves typically have sharp lobe tips, with bristles at the lobe tip. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly. Protobalanus, the Canyon live oak and its relatives, in southwest United States and northwest Mexico. Styles long acorns mature in 18 months, very bitter, inside of acorn shell hairless. Cerris, the Turkey oak and its relatives of Europe and Asia. Styles long acorns mature in 6 months, bitter, inside of hairless acorn shell (closely related to sect. Mesobalanus, the Hungarian oak and its relatives of Europe and Asia. ![]() Leaves mostly lack a bristle on lobe tips, which are usually rounded. Styles short acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless. Quercus (synonyms Lepidobalanus and Leucobalanus), the oaks of Europe, Asia and North America. The genus is divided into a number of sections: The "live oaks" (oaks with evergreen leaves) are not a distinct group, instead with their members scattered among the sections below. The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule each acorn contains one seed (rarely two or three) and takes 6-18 months to mature, depending on species. The flowers are catkins, produced in spring. Oaks have spirally arranged leaves, with a lobed margin in many species some have serrated leaves or entire leaves with a smooth margin. The genus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas. ![]() The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus (from Latin "oak tree"), which are listed in the List of Quercus species, and some related genera, notably Cyclobalanopsis and Lithocarpus. ![]()
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