derek-thomas/squad-v1.1-t5-question-generation huggingface dataset:
A 2011 discovery in the Canadian province of New Brunswick uncovered the earliest known plants to have grown wood, approximately 395 to 400 million years ago. Wood can be dated by carbon dating and in some species by dendrochronology to make inferences about when a wooden object was created.

Question: What year were the earliest plants that grew wood discovered? Question: In which Canadian province were the oldest woody plants found? Question: How many millions of years old were the plants that were discovered in New Brunswick? Question: If dendrochronology can't be used, what method would scientists employ to date wood?
People have used wood for millennia for many purposes, primarily as a fuel or as a construction material for making houses, tools, weapons, furniture, packaging, artworks, and paper. The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at that time.

Question: What has been the primary purpose of wood for millennia other than fuel? Question: What is often made of wood that provides shelter to people? Question: What could be made out of wood that could be used to fight off attackers? Question: What category of items often constructed from wood does a chair belong to? Question: For clues about the climate of a place, we can look at variation in isotopic abundances or what other thing?
Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. Where there are clear seasons, growth can occur in a discrete annual or seasonal pattern, leading to growth rings; these can usually be most clearly seen on the end of a log, but are also visible on the other surfaces. If these seasons are annual these growth rings are referred to as annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent.

Question: Where does wood come from? Question: What forms in a tree to increase its diameter? Question: What is the process of trees growing out to get bigger around called? Question: What do many places have four of that would cause growth rings in a tree? Question: If a place has annual seasons, what are the growth rings on the trees there called?
If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season is then known as the latewood or summerwood. However, there are major differences, depending on the kind of wood (see below).

Question: If a growth ring has differences over one season, would the part nearest the tree's center be narrower or wider? Question: Is earlywood usually lighter or darker than the part of the growth ring that forms later in the season? Question: What name, besides springwood, is used for the part of a growth ring formed in the beginning of the growing season? Question: Is summerwood the inner or outer portion of a growth ring? Question: If the opposite of springwood is summerwood, what's the opposite of earlywood?
A knot is a particular type of imperfection in a piece of wood; it will affect the technical properties of the wood, usually reducing the local strength and increasing the tendency for splitting along the wood grain, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood.

Question: What is the sort of circular imperfection in a piece of wood called? Question: What property of wood does a knot usually reduce in the wood around it? Question: In what direction is wood often sawn so that a knot appears as a solid circle that the grain flows around? Question: Are knots usually lighter or darker than the surrounding wood? Question: The direction of grain in a knot can differ by as much as how many degrees from the regular wood?
In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at the point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud.

Question: Other than the base of a side branch, what tree feature causes a knot? Question: What shape is the knot formed by a side branch's base? Question: Because a knot's shape is conical, what shape does a cross-section of it have? Question: What measurement of a stem determines a knot's inner tip placement?
During the development of a tree, the lower limbs often die, but may remain attached for a time, sometimes years. Subsequent layers of growth of the attaching stem are no longer intimately joined with the dead limb, but are grown around it. Hence, dead branches produce knots which are not attached, and likely to drop out after the tree has been sawn into boards.

Question: What will the lower limbs of a tree usually do during development? Question: For what length of time can a dead lower limb stay attached to a tree? Question: Rather than being joined to the limb that died, where do subsequent layers grow? Question: Are the knots that dead tree limbs form attached or not attached? Question: A detached knot will probably drop out of the wood when someone saws it into what?
In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.

Question: What's the process in which knots are classified called? Question: Along with firmness, soundness, and form, what property of a knot is classified? Question: What property of knots does the amount of time a branch stayed on a tree while the stem kept growing affect?
Knots do not necessarily influence the stiffness of structural timber, this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain.

Question: Depending on the placement and size of a knot, what property of structural timber can be affected? Question: What do stiffness and elastic strength depend on more than defects? Question: What is wood's breaking strength susceptible to? Question: What direction of compression in relation to its grain won't weaken wood with sound knots in it?
In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted, such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution, correctly applied during preparation, may do much to reduce this problem but it is difficult to control completely, especially when using mass-produced kiln-dried timber stocks.

Question: What positive visual component can knots sometimes add to decorative pieces? Question: What term is used to describe what knots can do to affect the finish of things made from wood even when they've been painted? Question: The stain from a knot bleeding is usually brownish or what other color? Question: In what stage of processing does knot primer need to be applied for maximum effectiveness? Question: Is bleed easy or difficult to control?
Heartwood (or duramen) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation occurs spontaneously (it is a genetically programmed process). Once heartwood formation is complete, the heartwood is dead. Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms, but only once.

Question: What's another word for "duramen"? Question: What is heartwood naturally resistant to? Question: How does heartwood formation occur due to its being genetically programmed? Question: What adjective describes fully formed heartwood? Question: Despite being considered dead, what can heartwood have one chemical reaction to?
Heartwood is often visually distinct from the living sapwood, and can be distinguished in a cross-section where the boundary will tend to follow the growth rings. For example, it is sometimes much darker. However, other processes such as decay or insect invasion can also discolor wood, even in woody plants that do not form heartwood, which may lead to confusion.

Question: What is the living wood in a tree called? Question: In what part of a tree's cross-section is heartwood visible? Question: What simple color distinction can heartwood have that makes it stand out from living wood in a tree? Question: Along with insect infestation, what process can discolor wood and make it look like heartwood? Question: What kind of plants never form heartwood?
Sapwood (or alburnum) is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. However, by the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm or more in diameter, before any heartwood begins to form, for example, in second-growth hickory, or open-grown pines.

Question: What term is interchangeable with "sapwood"? Question: Is sapwood the younger or older wood in a tree? Question: What essential liquid is the sapwood tasked with carrying around a tree? Question: How much of the wood in a tree is sapwood at some point in its life? Question: Does a tree growing quickly out in the open have thinner or thicker sapwood for its size than the same kind of tree in a dense forest?
The term heartwood derives solely from its position and not from any vital importance to the tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Others never form heartwood.

Question: What property of heartwood that has nothing to do with how important it is to trees got it its name? Question: If a tree starts forming heartwood right away, will its sapwood layer be thin or thick? Question: Does a sassafras tree typically have a thin or thick sapwood layer? Question: Does a beech tree usually have thin or thick sapwood? Question: Would a thin or a thick sapwood layer be found in a pine tree?
No definite relation exists between the annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is thicker in the upper portion of the trunk of a tree than near the base, because the age and the diameter of the upper sections are less.

Question: What part of a tree is the cross-sectional area of the sapwood approximately proportional to? Question: Are more rings necessary if they're narrow or wide? Question: As a tree grows bigger, if the sapwood layer doesn't increase in volume, what will it become? Question: In what part of the tree trunk is the sapwood layer thinnest? Question: Along with the smaller diameter of the upper trunk, what factor leads to thinner sapwood higher up a tree?
When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will however remain as knots. No matter how smooth and clear a log is on the outside, it is more or less knotty near the middle. Consequently, the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in the tree, may well be stronger than a piece of heartwood from the same tree.

Question: What usually covers the whole trunk of a very young tree? Question: What hides the stubs of a tree's lost limbs from being visible later in its life? Question: What evidence of the stubs of the limbs a tree loses can always be seen in the wood? Question: In a very old tree, are you more likely to find a lot of knots in the heartwood or the sapwood? Question: Since knots are defects that weaken lumber, would the heartwood or the sapwood from the same tree be stronger?
It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds, and in a few instances thousands, of years old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position.

Question: What part of a tree often stays impressively sound even when hundreds or thousands of years old? Question: What do broken limbs and deep wounds open a door for in a tree? Question: Decay can spread to all of what part of a tree? Question: What growth stage of insects bore holes into trees? Question: What evidence do some insect larvae leave in a tree forever?
If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks, maintain the same width of ring for hundreds of years. Upon the whole, however, as a tree gets larger in diameter the width of the growth rings decreases.

Question: In what stage of its life does a tree usually grow the fastest? Question: As a tree ages, do its growth rings usually get wider or narrower? Question: What part of a tree opens and spreads out more as it matures? Question: Is wood production of a tree lessened or increased as it ages? Question: Along with nutrients, what do trees growing in forests have to compete for?
Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even-textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true.

Question: When a big tree is cut up, will the pieces of wood differ or all be the same? Question: Besides big trees, what trees are more likely to have a range of different kinds of wood? Question: If you need really hard, strong wood from a small tree, would it likely be better to use the heartwood or sapwood? Question: In a large log, will the heartwood or sapwood usually be stronger and tougher?
In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently the contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color difference does not mean a dramatic difference in the mechanical properties of heartwood and sapwood, although there may be a dramatic chemical difference.

Question: When trees have a visible difference in color between sapwood and heartwood, which is darker? Question: Is the color difference between heartwood and sapwood usually very subtle or conspicuous? Question: What is deposited naturally in heartwood that changes its color? Question: What type of properties of heartwood and sapwood is often the same even if their colors are very different? Question: Although heartwood and sapwood might be similar mechanically, if their colors are very different, what other type of difference would they have?
Some experiments on very resinous Longleaf Pine specimens indicate an increase in strength, due to the resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby.

Question: What type of tree has resin that makes it stronger when it dries? Question: What's the funny name for resin-saturated heartwood? Question: What is fat lighter practically impervious to in addition to termites? Question: Since it's highly flammable, what do people often use little pieces of longleaf pine tree stumps for? Question: If spruce is shot full of crude resin and dried, which of its properties is increased?
Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood not infrequently appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood the reverse is commonly true. Except in the manner just stated the color of wood is no indication of strength.

Question: Which of the wood in a growth ring is usually darker? Question: Which property of a tree's wood that gives clues about its strength and hardness can be judged by it's color? Question: What category of trees show this difference greatly? Question: What type of woods might sometimes appear to have darker earlywood on a finished surface? Question: With the exception of earlywood/latewood difference in some types of trees, how much of an indication of strength is a wood's color?
Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness; however an attractive effect known as spalting produced by this process is often considered a desirable characteristic. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect.

Question: What condition does an abnormal color usually indicate in wood? Question: What other property can you assume of wood that is diseased? Question: What causes the black checked pattern in the wood of western hemlocks? Question: What animals cause the reddish-brown streaks of color in hickory wood? Question: What's the name for the pretty coloring effect caused in some wood by rot-producing fungi?
In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry.

Question: Air-dried wood keeps up to what percentage of the water in its cell walls? Question: What does wood retain in its cell walls despite being air-dried? Question: What kind of dried wood retains a small quantity of water but is considered absolutely dry?
The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect of common observation is in the softening action of water on rawhide, paper, or cloth. Within certain limits, the greater the water content, the greater its softening effect.

Question: Often the water in wood makes it more pliable and what else? Question: What type of action does water create in cloth? Question: What material sometimes used for dog chews reacts similarly to wood because of its water content? Question: What material we use to write or print on, like wood, becomes softer and more pliable when wet? Question: When water content increases within certain limits in wood, does is have a less or greater softening effect?
Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of the same size will.

Question: What will drying often increase in wood? Question: What type of wood can hold four times as much of a load when dried? Question: What color is also used interchangeably with "undried" for wood?