Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe. In a more general sense, deciduous means the dropping of a part that is no longer needed, or falling away after its purpose is finished. In plants it is the result of natural processes. Deciduous has a similar meaning when referring to animal parts, such as deciduous antlers in deer, or deciduous teeth, also known as baby teeth, in some mammals (including human children).

==Botany== In botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. This process is called abscission. In some cases leaf loss coincides with winter - namely in temperate or polar climates. In other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.

The converse of deciduous is evergreen, where green foliage is persistent year round. Plants that are intermediate may be called semi-deciduous; they lose old foliage as new growth begins. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods. Some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter; these dry persistent leaves are called marcescent leaves and are dropped in the spring as new growth begins.

Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination. The absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. Nevertheless, there is much less branch and trunk breakage from glaze ice storms when leafless, and plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.

Leaf drop or abscission involves complex physiological signals and changes within plants. The process of photosynthesis steadily degrades the supply of chlorophylls in foliage; plants normally replenish chlorophylls during the summer months. When autumn arrives and the days are shorter or when plants are drought-stressed, deciduous trees decrease chlorophyll pigment production, allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. The brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing. These other pigments include carotenoids that are yellow, brown, and orange. Anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, when sugars are trapped in the leaves after the process of abscission begins. Parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees simply fall off without turning the bright colors produced from the accumulation of anthocyanin pigments.

The beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf; it consists of layers of cells that can separate from each other. The cells are sensitive to a plant hormone called auxin that is produced by the leaf and other parts of the plant. When auxin coming from the leaf is produced at a rate consistent with that from the body of the plant, the cells of the abscission layer remain connected; in autumn, or when under stress, the auxin flow from the leaf decreases or stops, triggering cellular elongation within the abscission layer. The elongation of these cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It also forms a layer that seals the break, so the plant does not lose sap.

A number of deciduous plants remove nitrogen and carbon from the foliage before they are shed and store them in the form of proteins in the vacuoles of parenchyma cells in the roots and the inner bark. In the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers.

Function

Plants with deciduous foliage have both advantages and disadvantages compared to plants with evergreen foliage. Since deciduous plants lose their leaves to conserve water or to better survive winter weather conditions, they must regrow new foliage during the next suitable growing season; this uses resources which evergreens do not need to expend. Evergreens suffer greater water loss during the winter and they also can experience greater predation pressure, especially when small. Losing leaves in winter may reduce damage from insects; repairing leaves and keeping them functional may be more costly than just losing and regrowing them. Removing leaves also reduces cavitation which can damage xylem vessels in plants. This then allows deciduous plants to have xylem vessels with larger diameters and therefore a greater rate of transpiration (and hence CO2 uptake as this occurs when stomata are open) during the summer growth period.

Deciduous woody plants

The deciduous characteristic has developed repeatedly among woody plants. Trees include Maple, many Oaks, Elm, Aspen, and Birch, among others, as well as a number of coniferous genera, such as Larch and Metasequoia. Deciduous shrubs include honeysuckle, viburnum, and many others. Most temperate woody vines are also deciduous, including grapes, poison ivy, virginia creeper, wisteria, etc. The characteristic is useful in plant identification; for instance in parts of Southern California and the American Southeast, deciduous and evergreen oak species may grow side by side.

Periods of leaf fall often coincide with seasons: winter in the case of cool-climate plants or the dry-season in the case of tropical plants, however there are no deciduous species among tree-like monocotyledonous plants, e.g. palms, yuccas, and Dracaenas.

Regions

Forests where a majority of the trees lose their foliage at the end of the typical growing season are called deciduous forests. These forests are found in many areas worldwide and have distinctive ecosystems, understory growth, and soil dynamics.

Two distinctive types of deciduous forest are found growing around the world.

Temperate deciduous forest biomes are plant communities distributed in North and South America, Asia and Europe. They have formed under climatic conditions which have great seasonable temperature variability with growth occurring during warm summers and leaf drop in autumn and dormancy during cold winters. These seasonally distinctive communities have diverse life forms that are impacted greatly by the seasonality of their climate, mainly temperature and precipitation rates. These varying and regionally different ecological conditions produce distinctive forest plant communities in different regions.

Tropical and subtropical deciduous forest biomes have developed in response not to seasonal temperature variations but to seasonal rainfall patterns. During prolonged dry periods the foliage is dropped to conserve water and prevent death from drought. Leaf drop is not seasonally dependent as it is in temperate climates, and can occur any time of year and varies by region of the world. Even within a small local area there can be variations in the timing and duration of leaf drop; different sides of the same mountain and areas that have high water tables or areas along streams and rivers can produce a patchwork of leafy and leafless trees.

References

Category:Botany Category:Plants and pollinators

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Name	Ken Jeong
Birth date	July 13, 1969
Birth place	Detroit, Michigan, USA
Birth name	Kendrick Kang-Joh Jeong
Alma mater	Duke UniversityUniversity of North Carolina, Chapel Hill
Occupation	Actor, comedian, physician
Yearsactive	1997–present
Website	}}

Dr. Kendrick Kang-Joh “Ken” Jeong, MD (born July 13, 1969) also known as Dr. Ken, is an American comedian, actor, and physician. He is best known for his role as Leslie Chow in ''The Hangover'' & ''The Hangover Part II'' and as Ben Chang on the NBC comedy series ''Community''.

Early years

Jeong was born in Detroit, Michigan, the son of South Korean immigrants Young and D.K. Jeong, who was a professor at North Carolina A&T; State University in Greensboro, North Carolina. Jeong was raised in Greensboro and attended Walter Hines Page High School, where he took part in the High IQ team, played violin in the orchestra, and was elected to student council. He graduated at 16 and his achievements earned him Greensboro's Youth of the Year award.

Career

Medicine

He completed his undergraduate studies at Duke University in 1990 and attained his medical degree at the University of North Carolina at Chapel Hill in 1995. He then completed his Internal Medicine residency at Ochsner Medical Center in New Orleans while developing his stand-up comedy.

Show business

He won the Big Easy Laff-Off, of which NBC president Brandon Tartikoff and The Improv founder Budd Friedman were judges. They both urged Jeong to move to Los Angeles, and he began performing regularly at the Improv and Laugh Factory comedy clubs.

Jeong's background in theater and improv has led to several television appearances, including NBC's ''The Office'', HBO's ''Entourage'' and ''Curb Your Enthusiasm''. Ken made his feature film debut as Dr. Kuni in Judd Apatow's ''Knocked Up'' which proved to be his breakout performance. Subsequently, he has appeared in ''Pineapple Express''; ''Role Models'' as King Argotron; ''All About Steve''; ''The Goods: Live Hard, Sell Hard''; ''Couples Retreat''; and as Mr. Chow in ''The Hangover'' and ''The Hangover Part II''. He co-starred in ''Zookeeper'' and ''Transformers: Dark of the Moon'', released in summer 2011.

He attacked (kayfabe) pro wrestler John Cena with a cane on the August 3, 2009 episode of ''WWE Raw''.

Jeong is a series regular as Señor Chang on NBC's sitcom ''Community''.

Jeong was nominated for two 2010 ''MTV Movie Awards'', winning the award for ''Best WTF Moment'' as well as being nominated for ''MTV Movie Award for Best Villain'' for ''The Hangover''.

Jeong was also nominated for "Breakout Star Male" for ''Community'' at the ''2010 Teen Choice Awards''.

In the fall of 2010, Adidas basketball began a wide-ranging marketing campaign in which Jeong stars as the character "Slim Chin" alongside NBA stars Dwight Howard and Derrick Rose.

On May 22, 2011, Jeong hosted the ''2011 Billboard Music Awards'' in Las Vegas on ABC.

On June 15, 2011, Jeong was featured in a Hands Only CPR PSA campaign from the American Heart Association.

Ken Jeong will star in and produce the film The Chung Factor, which was purchased by Lionsgate on October 25, 2011.

Personal life

Jeong's wife, Tran Ho, a Vietnamese American, is also a doctor. Together, they have twin daughters, Alexa and Zooey.

Filmography

colspan="4" style="background: LightSteelBlue;"	Film
! Year	! Film	! Role	! Other notes
	2007	''Knocked Up''	Dr. Kuni
		Employment Agent
	Ken
''Role Models''	King Argotron
''The Goods: Live Hard, Sell Hard''	Teddy Dang
''All About Steve''	Angus
''Couples Retreat''	Therapist No.2
	''How to Make Love to a Woman''	Curtis Lee
''Furry Vengeance''	Neal Lyman
''Despicable Me''	Talk Show Host	Voice role
''Vampires Suck''	Daro
	''Big Mommas: Like Father, Like Son''	Mailman	Cameo
	Venom
''The Hangover Part II''
''Transformers: Dark of the Moon''	Jerry Wang
''''	Punch Teacher host	Cameo
2012	''Pain & Gain''	Johnny Wu
2013	''The Hangover Part III''
Television
! Year	! Title	! Role	! Notes
1997	''The Big Easy''	Dr. Tang	Episode: Night Music
1998	''Black Jaq''	Kurt	TV-pilot
2001	''The Downer Channel''	Store Owner	Episode: 1.2
2002	''Girls Behaving Badly''	Various characters
2003	''Cedric the Entertainer Presents''	Asian Thunder
2003–2005	''MADtv''	Various characters	4 episodes
		Gynecologist
''Crossing Jordan''	Steve Choi	Episode: Slam Dunk
''Grounded for Life''	Owner
	''Two and a Half Men''	Male Nurse
''Mind of Mencia''	Ken
''Jimmy Kimmel Live!''	Astronaut	Episode: July 29, 2005
	Bill
		Roido's Interpreter	TV-pilot
	Coffee Shop Manager
	''The Shield''	Skip Osaka
''Curb Your Enthusiasm''	Man in Jersey No.1
''Boston Legal''	Coroner Myron Okubo
	''Held Up''	Doctor	TV-pilot
'''Til Death''	Dr. Park	List of 'Til Death episodes#Season 2: 2007-2008
''[[Worst Week''	Phil	List of Worst Week episodes#Season 1: 2008-2009
	''Off Duty''	Jackie Chan	TV-pilot
''[[American Dad!''	Dr. Perlmutter	Family Affair (American Dad!)
''[[Party Down''	Alan Duk	List of Party Down episodes#Season 1: 2009
''[[Men of a Certain Age''	Kuo
2009–present			Series regular
2012	''Mary Shelley's Frankenhole''	Everybody

References

External links

Category:1969 births Category:Actors from Michigan Category:American comedians Category:American film actors Category:American physicians Category:American television actors Category:Living people Category:People from Detroit, Michigan Category:People from Greensboro, North Carolina Category:Duke University alumni Category:University of North Carolina at Chapel Hill alumni Category:American_actors_of_Korean_descent

da:Ken Jeong de:Ken Jeong es:Ken Jeong fr:Ken Jeong gl:Ken Jeong ko:켄 정 it:Ken Jeong nl:Ken Jeong ja:ケン・チョン pt:Ken Jeong ru:Джонг, Кен sv:Ken Jeong