romikgosai/squad_modified_2 huggingface dataset:
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.

Q1: If a tree starts forming heartwood right away, will its sapwood layer be thin or thick?
A1: thin
Q2: What property of heartwood that has nothing to do with how important it is to trees got it its name?
A2: position
Q3: Does a beech tree usually have thin or thick sapwood?
A3: thick
Q4: Does a sassafras tree typically have a thin or thick sapwood layer?
A4: Thin
Q5: Would a thin or a thick sapwood layer be found in a pine tree?
A5: thick
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.

Q1: What part of a tree is the cross-sectional area of the sapwood approximately proportional to?
A1: crown
Q2: Are more rings necessary if they're narrow or wide?
A2: narrow
Q3: As a tree grows bigger, if the sapwood layer doesn't increase in volume, what will it become?
A3: thinner
Q4: In what part of the tree trunk is the sapwood layer thinnest?
A4: near the base
Q5: Along with the smaller diameter of the upper trunk, what factor leads to thinner sapwood higher up a tree?
A5: age
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.

Q1: What usually covers the whole trunk of a very young tree?
A1: limbs
Q2: What evidence of the stubs of the limbs a tree loses can always be seen in the wood?
A2: knots
Q3: In a very old tree, are you more likely to find a lot of knots in the heartwood or the sapwood?
A3: heartwood
Q4: What hides the stubs of a tree's lost limbs from being visible later in its life?
A4: Subsequent growth
Q5: Since knots are defects that weaken lumber, would the heartwood or the sapwood from the same tree be stronger?
A5: sapwood
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.

Q1: What do broken limbs and deep wounds open a door for in a tree?
A1: decay
Q2: Decay can spread to all of what part of a tree?
A2: the trunk
Q3: What growth stage of insects bore holes into trees?
A3: larvae
Q4: What part of a tree often stays impressively sound even when hundreds or thousands of years old?
A4: inner heartwood
Q5: What evidence do some insect larvae leave in a tree forever?
A5: tunnels
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.

Q1: In what stage of its life does a tree usually grow the fastest?
A1: youth
Q2: As a tree ages, do its growth rings usually get wider or narrower?
A2: narrower
Q3: What part of a tree opens and spreads out more as it matures?
A3: crown
Q4: Is wood production of a tree lessened or increased as it ages?
A4: lessened
Q5: Along with nutrients, what do trees growing in forests have to compete for?
A5: light
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.

Q1: When a big tree is cut up, will the pieces of wood differ or all be the same?
A1: differ
Q2: In a large log, will the heartwood or sapwood usually be stronger and tougher?
A2: heartwood
Q3: If you need really hard, strong wood from a small tree, would it likely be better to use the heartwood or sapwood?
A3: sapwood
Q4: Besides big trees, what trees are more likely to have a range of different kinds of wood?
A4: mature
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.

Q1: When trees have a visible difference in color between sapwood and heartwood, which is darker?
A1: heartwood
Q2: What is deposited naturally in heartwood that changes its color?
A2: chemical substances
Q3: Is the color difference between heartwood and sapwood usually very subtle or conspicuous?
A3: conspicuous
Q4: What type of properties of heartwood and sapwood is often the same even if their colors are very different?
A4: mechanical
Q5: Although heartwood and sapwood might be similar mechanically, if their colors are very different, what other type of difference would they have?
A5: chemical
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.

Q1: What type of tree has resin that makes it stronger when it dries?
A1: Longleaf Pine
Q2: What's the funny name for resin-saturated heartwood?
A2: fat lighter
Q3: What is fat lighter practically impervious to in addition to termites?
A3: rot
Q4: If spruce is shot full of crude resin and dried, which of its properties is increased?
A4: strength
Q5: Since it's highly flammable, what do people often use little pieces of longleaf pine tree stumps for?
A5: kindling
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.

Q1: Which of the wood in a growth ring is usually darker?
A1: latewood
Q2: Which property of a tree's wood that gives clues about its strength and hardness can be judged by it's color?
A2: density
Q3: What category of trees show this difference greatly?
A3: coniferous
Q4: What type of woods might sometimes appear to have darker earlywood on a finished surface?
A4: ring-porous
Q5: With the exception of earlywood/latewood difference in some types of trees, how much of an indication of strength is a wood's color?
A5: no indication
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.

Q1: What condition does an abnormal color usually indicate in wood?
A1: diseased
Q2: What other property can you assume of wood that is diseased?
A2: unsoundness
Q3: What causes the black checked pattern in the wood of western hemlocks?
A3: insect attacks
Q4: What animals cause the reddish-brown streaks of color in hickory wood?
A4: birds
Q5: What's the name for the pretty coloring effect caused in some wood by rot-producing fungi?
A5: spalting
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.

Q1: What does wood retain in its cell walls despite being air-dried?
A1: water
Q2: Air-dried wood keeps up to what percentage of the water in its cell walls?
A2: 16
Q3: What kind of dried wood retains a small quantity of water but is considered absolutely dry?
A3: oven-dried
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.

Q1: Often the water in wood makes it more pliable and what else?
A1: softer
Q2: What material sometimes used for dog chews reacts similarly to wood because of its water content?
A2: rawhide
Q3: What material we use to write or print on, like wood, becomes softer and more pliable when wet?
A3: paper
Q4: When water content increases within certain limits in wood, does is have a less or greater softening effect?
A4: greater
Q5: What type of action does water create in cloth?
A5: softening
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.

Q1: What will drying often increase in wood?
A1: strength
Q2: What color is also used interchangeably with "undried" for wood?
A2: green
Q3: What type of wood can hold four times as much of a load when dried?
A3: spruce
The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected.

Q1: What type of "ultimate" strength is one of the two types increased the most by drying wood?
A1: crushing
Q2: What property of wood is least affected by drying?
A2: elasticity
Q3: Is strength at elastic limit in endwise compression or stress at elastic limit in cross-bending increased more by drying wood?
A3: strength at elastic limit in endwise compression
Q4: Is the strength of the modulus of rupture or elasticity increased more when wood is dried?
A4: modulus of rupture
Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It consists of cells, and the cell walls are composed of micro-fibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%).

Q1: Along with hygroscopic, cellular, and anisotropic, how is the material of wood described?
A1: heterogeneous
Q2: What does wood consist of?
A2: cells
Q3: What part of wood's cells are composed of cellulose and hemicellulose?
A3: walls
Q4: What makes up 40-50% of the cell walls in wood?
A4: cellulose
Q5: What substance is hemicellulose impregnated with?
A5: lignin
In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than that of most hardwoods. There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example.

Q1: What type of cells makes up most wood cells in coniferous trees?
A1: tracheids
Q2: Are hardwood or softwood species more uniform in structure?
A2: softwood
Q3: What are the visible vessels in hardwoods commonly called?
A3: pores
Q4: What hardwood that starts with the letter "O" would have pores?
A4: oak
Q5: Besides oak, what's an example of a hardwood with prominent pores?
A5: ash
The structure of hardwoods is more complex. The water conducting capability is mostly taken care of by vessels: in some cases (oak, chestnut, ash) these are quite large and distinct, in others (buckeye, poplar, willow) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous.

Q1: Is the structure of hardwood simple or complex?
A1: complex
Q2: What handles most of the water conduction in hardwoods?
A2: vessels
Q3: Are the vessels in chestnut wood large or small?
A3: large
Q4: In wood from a willow tree, what would you need to use to see the tiny vessels?
A4: a hand lens
Q5: Besides ring-porous, what's the other class hardwoods are often divided into?
A5: diffuse-porous
In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, the larger vessels or pores (as cross sections of vessels are called) are localised in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fibers are the elements which give strength and toughness to wood, while the vessels are a source of weakness.[citation needed]

Q1: What species of hardwood are hickory and mulberry trees?
A1: ring-porous
Q2: In what season do the growth-rings of ring-porous species form with larger vessels localized?
A2: spring
Q3: In what season does the part of the growth-ring with smaller vessels form in ring-porous species?
A3: summer
Q4: What fibers does the summer's section of growth-ring have more of?
A4: wood fibers
Q5: Along with strength, what property do wood fibers lend to wood?
A5: toughness
In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are alder, basswood,[citation needed] birch, buckeye, maple, willow,and the Populus species such as aspen, cottonwood and poplar. Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group.[citation needed]

Q1: What kind of woods have pores that are uniformly sized?
A1: diffuse-porous
Q2: What species do aspen, cottonwood, and poplar trees belong to?
A2: Populus
Q3: With walnut, what's another tree in the intermediate group?
A3: cherry
Q4: What capability is spread through the growth ring in ring-porous species?
A4: water conducting
Q5: Is maple wood diffuse-porous or ring-porous?
A5: diffuse-porous
In temperate softwoods there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength is in the walls, not the cavities. Hence the greater the proportion of latewood the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring.

Q1: What kind of softwoods often have significant differences in their earlywood and latewood?
A1: temperate
Q2: Is latewood denser or less dense than earlywood?
A2: denser
Q3: Does strength come from the walls or cavities of wood cells?
A3: walls
Q4: Are the cell walls of earlywood thick or thin?
A4: thin
Q5: What general size are the cavities in the cells of very dense latewood?
A5: very small
If a heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines, on the other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood.

Q1: Comparing a heavy and a lightweight piece of wood from a pine, which would have a greater proportion of latewood?
A1: heavy
Q2: What feature of a piece of pine with more latewood would be more clear and pronounced?
A2: growth rings
Q3: What type of tree has very little contrast between parts of its growth rings?
A3: white pines
Q4: Is white pine easy or difficult to work with because of its texture?
A4: easy
Q5: What kind of pines have very deep, darkly colored hardwood that stands out against the light earlywood?
A5: hard pines
It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain but little. One can judge comparative density, and therefore to some extent strength, by visual inspection.

Q1: Having a high proportion of latewood isn't all that matters; what else is important?
A1: quality
Q2: What can we judge in wood just by looking at it?
A2: comparative density
Q3: What property of wood could we project some indication of by looking at its density?
A3: strength
Q4: What could we call some specimens with a high proportion of latewood that explains why they weigh less than specimens with much less latewood?
A4: porous
No satisfactory explanation can as yet be given for the exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of the wood formed, though it is not possible to formulate a rule governing it. In general, however, it may be said that where strength or ease of working is essential, woods of moderate to slow growth should be chosen.

Q1: What facet of wood is affected to some degree by the place where the tree grows?
A1: character
Q2: If you want wood that's easy to work with, what kind of growth would you want the tree to have?
A2: moderate to slow
Q3: What species of tree can be said to growth ring proportions that aren't determined just by their rate of growth?
A3: conifers
Q4: What counterpart of earlywood are scientists still trying to explain the formation of?
A4: latewood
Q5: While there is some relationship between where and how a tree grows, what can't anyone formulate to govern it?
A5: a rule
In ring-porous woods each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before.

Q1: What kind of woods always have very clearly marked seasonal growth?
A1: ring-porous
Q2: What size pores form early in ring-porous woods' growing season?
A2: large
Q3: When does the denser tissue the new pores abut come from?
A3: the year before
In the case of the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.

Q1: Ring-porous hardwoods have a clear relationship between their properties and what other factor?
A1: rate of growth
Q2: Is harder, heavier wood indicated by narrower or wider growth rings?
A2: wider
Q3: What kind of wood with a name that starts with "H" is a ring-porous hardwood?
A3: hickory
Q4: If the growth rings are wider, was the growth of the tree slower or more rapid?
A4: more rapid
Q5: What is the only kind of wood that will definitely be harder and stronger when it grows faster?
A5: ring-porous