Pinus taeda, commonly known as loblolly pine, is one of several native to the Southeastern United States, from East Texas to Florida, and north to southern New Jersey.[ U.S. Forest Service surveys found that loblolly pine is the second-most common species of tree in the United States, after red maple.]
Loblolly pine is the first among over 100 species of Pinus to have its complete genome sequenced. As of March 2014, it was the organism having the largest sequenced genome size. Its genome, with 22 billion base pairs, is seven times larger than human genome.
Description
Loblolly pine can reach a height of with a diameter of . Exceptional specimens may reach tall, the largest of the southern pines. Its needles are in bundles (fascicles) of three, sometimes twisted, and measure long, an intermediate length for southern pines, shorter than those of the longleaf pine or slash pine, but longer than those of the Pinus echinata and Pinus glabra. The needles usually last up to two years before they fall, which gives the species its evergreen character.
Although some needles fall throughout the year due to severe weather, insect damage, and drought, most needles fall during the autumn and winter of their second year. The Conifer cone are green, ripening pale buff-brown, in length, broad when closed, opening to wide, each scale bearing a sharp spine long.[Farjon, A. (2005). Pines: Drawings and Descriptions of the Genus Pinus, ed.2. Brill, Leiden .]
Bark is reddish brown and deeply fissured into irregular, broad, scaly plates on older trees. Branches are reddish-brown to dark yellowish brown.
Loblolly pines are one of the fastest growing pines making it a valuable species in the lumber industry. The lumber marketed as yellow pine lumber and similar usage to other southern pines such as the more stronger Longleaf and Shortleaf pines. They are also used as pulpwood.[
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/ref> The tallest loblolly pine currently known, which is tall, and the largest, which measures in volume, are in Congaree National Park.
File:Pinus taeda cones.jpg|Mature unopened female cones
File:Tree Types and Barks 004.jpg|Bark on a mature tree
File:P. taeda old growth.jpg|A gigantic old-growth loblolly pine, note human for scale
Etymology and taxonomy
The word "loblolly" is a combination of "lob", referring to thick, heavy bubbling of cooking porridge, and "lolly", an old British dialect word for "broth, soup, or any other food boiled in a pot". In the southern United States, the word is used to mean "a mudhole; a mire," a sense derived from an allusion to the consistency of porridge. Hence, the pine is named as it is generally found in lowlands and swampy areas.[ Loblolly pines grow well in acidic clay soil, which is common throughout the South, thus are often found in large stands in rural places.
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Other old names, now rarely used, include oldfield pine due to its status as an Ruderal species of abandoned fields; bull pine due to its size (several other are also often so named, especially large isolated specimens); rosemary pine due to loblolly's distinctive fragrance compared to the other southern pines; and North Carolina pine.
For the scientific name, is the Latin name for the pines and refers to the resinous wood.
Ecology
With the advent of wildfire suppression, loblolly pine has become prevalent in some parts of the Deep South that were once dominated by longleaf pine and, especially in northern Florida, Pinus elliottii.[Richardson, D. M., & Rundel, P. W. (1998). Ecology and biogeography of Pinus: an introduction. Pages 3–46 in Richardson, D. M., ed. Ecology and biogeography of Pinus. Cambridge University Press .]
Its rate of growth is rapid, even among the generally fast-growing southern pines. The yellowish, wood is prized for lumber, but is also used for wood pulp. This tree is commercially grown in extensive plantations.
Loblolly pine is the pine of the Lost Pines Forest around Bastrop, Texas, and in McKinney Roughs Nature Park along the Texas Colorado River. These are isolated populations on areas of soil, surrounded by that are poor for pine growth.
A study using loblolly pines showed that higher atmospheric carbon dioxide levels may help the trees to endure ice storms better.[ Greenhouse Gas Good for Some Trees - LiveScience.com]
Notable trees
The famous "Eisenhower Tree" on the 17th hole of Augusta National Golf Club was a loblolly pine. U.S. President Dwight D. Eisenhower, an Augusta National member, hit the tree so many times that at a 1956 club meeting, he proposed that it be cut down. Not wanting to offend the President, the club's chairman, Clifford Roberts, immediately adjourned the meeting rather than reject the request outright. In February 2014, an ice storm severely damaged the Eisenhower Tree. The opinion of was that the tree could not be saved and should be removed, which it subsequently was.
The "Morris Pine" is located in southeastern Arkansas; it is over 300 years old with a diameter of and a height of .
Loblolly pine seeds were carried aboard the Apollo 14 flight. On its return, the seeds were planted in several locations in the US, including the grounds of the White House. , a number of these remain alive.
Genome
Pines are the most common conifers and the genus Pinus consists of more than 100 species. Sequencing of their genomes remained a huge challenge because of the high complexity and size.[
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The loblolly pine genome is made up of 22.18 billion base pairs, which is more than seven times that of humans.[ Conifer genomes are known to be full of repetitive DNA, which make up 82% of the genome in loblolly pine (compared to only 50% in humans). The number of genes is estimated at 50,172, of which 15,653 are already confirmed. Most of the genes are Gene duplication. Some genes have the longest introns observed among fully sequenced plant genomes.]
Inbreeding depression
are predominantly outcrossing, but lack genetic self-incompatibility. Loblolly pine, like most gymnosperms, exhibits high levels of inbreeding depression, especially in the embryonic stage. The loblolly pine harbors an average load of at least eight lethal equivalents.
See also
External links
