The Fagaceae, or oak family, is a very slow evolving clade compared to other angiosperms, and the patterns of hybridization and introgression in Quercus pose a great challenge to the concept of a species since a species is often defined as a group of “ actually or potentially interbreeding populations which are reproductively isolated from other such groups .” By this definition, many species of Quercus would be lumped together according to their geographic and ecological habitat, despite clear distinctions in morphology and, to a large extent, genetic data.

The family Fagaceae, or beech family, comprises about 900 species of both evergreen and deciduous trees and shrubs, which are characterized by alternate simple leaves with pinnate venation, unisexual flowers in the form of catkins, and fruit in the form of cup-like ( cupule ) nuts.

The Fagaceae are widely distributed across the Northern Hemisphere.

Members of the Fagaceae ( such as Fagus grandifolia, Castanea dentata and Quercus alba in the Northeastern United States, or Fagus sylvatica, Quercus robur and Q. petraea in Europe ) are often ecologically dominant in Northern temperate forests.

In the past, they were included in the family Fagaceae, but genetic tests by the Angiosperm Phylogeny Group revealed them to be genetically distinct, and they are now included in a family their own, the Nothofagaceae.

The main tree species are members of beech family ( Fagaceae ).

Some forests are dominated by Lauraceae, while in others evergreen laurophyll trees of the beech family ( Fagaceae ) are predominant, including ring-cupped oaks ( Quercus subgenus Cyclobalanopsis ), chinquapin ( Castanopsis ) and tanoak ( Lithocarpus ).

Trees of the Laurel family are less prominent, limited to Ocotea or Beilschmiedia due to exceptional biological and paleoecological interest and the enormous biodiversity mostly but with many endemic species, and the members of the beech family ( Fagaceae ) are absent.

They are found in many plant families, including Betulaceae, Fagaceae, Moraceae, and Salicaceae.

The most common tree families are Beech Fagaceae, Laurel ( Lauraceae ), Camellia ( Theaceae ), Magnolia ( Magnoliaceae ), Elaeocarpaceae, and Witchhazel Hamamelidaceae.

These small moths are leaf-miners in the caterpillar stage, feeding mainly on Fagaceae ( Tischeria and Coptotriche ), Asteraceae and Malvaceae ( Astrotischeria ), and some also on Rhamnaceae, Tiliaceae and Rosaceae.

Trigonobalanus is a genus of three species of evergreen trees in the family Fagaceae, related to beeches and chestnuts.

The older Cronquist system only included four families ( Betulaceae, Corylaceae, Fagaceae, Ticodendraceae ; Corylaceae now being included within Betulaceae ); this arrangement is followed by, for example, the World checklist of selected plant families ( see external link below ).

Special collections include Amaryllidaceae, Apiaceae, Asclepiadoideae, Asteraceae, Crassulaceae, Droseraceae, Fabaceae, Fagaceae, Iridaceae, Geraniaceae, Lamiaceae, Lentibulariaceae, Liliaceae, Palmae, Pinaceae, Scrophulariaceae, Nepenthaceae, and Sarraceniaceae.

Chestnut ( Castanea ), some species called chinkapin or chinquapin, is a genus of eight or nine species of deciduous trees and shrubs in the beech family Fagaceae, native to temperate regions of the Northern Hemisphere.

Beech ( Fagus ) is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.

The acorn, or oak nut, is the nut of the oaks and their close relatives ( genera Quercus and Lithocarpus, in the family Fagaceae ).

But more important, and the thing which the casual traveler and the blind sojourner often do not see, is that these places and activities are often the settings in which Persians exercise their extraordinary aesthetic sensibilities.

The men crying love poems in an orchard on any summer's night are as often as not the lutihaw, mustachioed toughs who spend most of their lives in and out of the local prisons, brothels, and teahouses.

Our collective policies, group and national, are similarly based on voodoo, but here we often lack even the empirically successful rituals and are still engaged in determing them.

Southern Liberals ( there are a good many ) -- especially if they're rich -- often exhibit blithe insouciance.

But when these expectations are once too often ground into the dust, innocence can falter, since its strength is according to the strength of him who possesses it.

He explains that there are sometimes honorable courtiers, but that too often a man who succeeds at court does not hesitate to sacrifice his Sovereign and nation to his own avarice and ambition.

By the same test predispositions destructive of human personality exercise their most sinister impact, with the result that men of good will are often trapped and nullified.

The continuities, contrasts, and similarities discernible when past and present are surveyed together are inexhaustible and the one is often understood through the other.

Tolerance and compromise, social justice and civil liberty, are today too often in short supply for one to be overly critical of Trevelyan's emphasis on their central place in the English tradition.

That he read some of the books assigned to him with a studied carefulness is evident from his notes, which are often so full that they provide an unquestionable basis for the identification of reviews that were printed without his signature.

The purely cognitive or informational problems are often acute.

The religious quest is often intense and deep, and there are students on every campus who are seriously wrestling with the most profound questions of meaning and value.

Those who do have occasion to deal with the invasions in a more general way, like T.W. Shore and Arthur Wade-Evans, are on the side of a gradual and often peaceful Germanic penetration into Britain.

In addition, there are many areas of the human situation besides the impact of science and technology which are examined, for science-fiction dystopias often extrapolate political, social, economic tendencies only indirectly related to science and technology.

If only this could be done more often -- with such heartening results -- many of the earth's `` big problems '' would shrink to the insignificances they really are.

Production assistance often takes the form of locating tools or materials which are urgently needed.

More often, these offices are restricted to the gathering of empirical data.

The answers they give can often pave the way to performance increases and, quite often, are necessary for completing entry blanks for different events.

Although the site may not contain the features themselves, there are often opportunities to include them as additional interest to the site.

that is, he is suspect, guilty, punishable, as is anyone in Mann's stories who produces illusion, and this is true even though the constant elements of the artist-nature, technique, magic, guilt and suffering, are divided in this story between Jacoby and Lautner.

Students are approximately equally divided between those who regard vocational preparation as the primary goal of an ideal education and those who chose a general liberal education.

The long-range aspects of this program are divided into four distinct phases: basic mapping, inventory, analysis and plan and policy formation.

In recent months, much attention has been given to the probable extent of the current downtrend in business and economists are somewhat divided as to the outlook for the near future.

When prepositional complements are divided as in what are you looking for??

How to achieve this objective is a problem, but we are not divided on what we want.

This is a problem, but we are not divided over its importance or by its existence.

Instead, all of the total costs are treated as variable costs, although these costs are divided into costs that are deemed to be functions of different variables.

The compounds are divided according to composition into seven categories.

Actinopods are divided into radiolaria and heliozoa ( itself a polyphyletic grouping ).

Amphibia in its widest sense ( sensu lato ) was divided into three subclasses, two of which are extinct:

The Lissamphibia, superorder Salientia, are traditionally divided into three orders, but an extinct salamander-like family, the Albanerpetontidae, is now considered part of the Lissamphibia alongside the superorder Salientia.

Anura is divided into three suborders which are broadly accepted by the scientific community but the relationships between some families remains unclear.

Below this crack is another group of eleven parallel lines, again divided into two sections by a line perpendicular to them, but with the semicircle at the top of the intersection ; the third, sixth and ninth of these lines are marked with a cross where they intersect with the vertical line.

The numerical value of K < sub > a </ sub > is equal to the concentration of the products divided by the concentration of the reactants, where the reactant is the acid ( HA ) and the products are the conjugate base and H < sup >+</ sup >.

The Agnostida are divided into two suborders — Agnostina and Eodiscina — that are then divided into a number of families.

Archaeological interpretations of the Chaco road system are divided between an economic purpose and a symbolic, ideological role linked to ancestral Puebloan beliefs.

divided into bins and the number of occurrences within each bin are

The arms of the city are divided into two halves.