Yew

[DC]

Anybody have any idea why Yew is so good in compression? It's such a soft wood you would think it would crush easily.

[Del the cat]

Short answer... I dunno 
long answer... It has evolved that way so that Yew trees don't buckle, slump and fall over.
I've noticed on some big Willows where they lean, you can see the buckling and thickening round the base where the wood has failed in compression repeatedly and grown over.
It's easy to confuse soft, light, stiff, flexible, strong and other properties, especially when comparing along and across the grain.
Del

[Marc St Louis]

It can be soft but I have occasionally worked some that was as hard as Maple.

[Badger]

  It has a higher elasticity than most woods and decent stiffness. This equates to a lower mass bow that won't take as much set.

[DC]

  It has a higher elasticity than most woods and decent stiffness. This equates to a lower mass bow that won't take as much set.

So you're thinking that it compresses more than say, Ipe, but the elasticity allows it to recover?

[DC]

It can be soft but I have occasionally worked some that was as hard as Maple.

Yeah, I like working that stuff. Feels like it's already been heat treated.

[DC]

Short answer... I dunno 
long answer... It has evolved that way so that Yew trees don't buckle, slump and fall over.
I've noticed on some big Willows where they lean, you can see the buckling and thickening round the base where the wood has failed in compression repeatedly and grown over.
It's easy to confuse soft, light, stiff, flexible, strong and other properties, especially when comparing along and across the grain.
Del

I realised after I posted this that, "I dunno." was probably the correct answer but I'm liking Badger's answer.

[Dances with squirrels]

Because Yew is magical.

[willie]

http://www.primitivearcher.com/smf/index.php?topic=55682.0

[DC]

So Willie, you're thinkin' that Yew has a greater fibril angle even in more mature wood?

[willie]

i will take their word for it....
in post 33 of that thread, Joachim posted a link to a paper he uploaded to google drive.

Ingela Bjurhager*, E. Kristofer Gamstedt, Daniel Keunecke, Peter Niemz and Lars A. Berglund

Mechanical performance of yew (Taxus baccata L.)
from a longbow perspective

Conclusions
Tensile, compression, and 4PB-tests tests were performed
on yew, pine, and juniper, and the stiffness and strength
were determined. Whereas tensile strength did not differ
between the three species, yield stress in compression was
higher for yew. Moreover, yew displayed a surprisingly low
stiffness, considering its high density. This can probably
be ascribed to its unusually high MFA. The experimental

data in combination with a simple bow model showed
that yew has a high toughness, which means that a large
amount of elastic energy can be stored in a yew bow and
transferred to the arrow. Consequently, a bow made from
yew is likely to have a larger range, compared with bows
from other wood species. The 4PB-tests in this study also
showed that yew could withstand high strains in the
plastic region before failure. Bows are often subjected
to bending beyond the elastic limit, and therefore this is
another desirable trait. The remarkable ability of yew to
withstand large deformations and resist crack formation
has been ascribed to the high MFA and a high amount of
rays in the radial direction, where the later results in a
fiber bridging behavior.
It was found that heartwood performed better in terms
of yield stress in compression than sapwood. However,
the difference was not related to the extractives. Instead,
the difference is probably related to morphologic traits
because yew heartwood is likely to be composed mainly of
juvenile wood, which differs from mature wood in terms
of MFA and density. Based on our experimental and model
results, the guideline for making a bow with maximum
performance is to include approximately 30–50% juvenile
wood on the belly side. Moreover, the stiffness and yield
stress in compression for the juvenile wood should be as
high as possible compared with the mature wood on the
backside of the bow.

[Ballasted_Bowyer]

Although wood properties do make a difference in suitability as a bow wood, there are surprises from an engineering standpoint. Between two woods with the same modules of elasticity, the amount of stress required to produce a unit of bending response, the wood with the higher elastic limit is the better species for archery. But wait, there's more! Between two woods with the same MOE and the same EL, the less dense wood is better because it will be lighter. Most of the common hardwoods in North America have similar ratios. However, yew is lighter for its MOE than average and still has a high MOR. Garyanna Oak is denser than Yew but has a better MOE/MOR ratio. Osage Orange also stands out. I think I posted a table. I will see if I can find it. Ultimately, within the group of woods that are good or excellent for archery, individual quality of stave and workmanship outweigh species in my opinion.

[Ballasted_Bowyer]

I guess I didn't post a table but here is a discussion about the mysteries of bow wood that might give some perspective. There is an essay mentioned that is enlightening.

Oops:

http://www.primitivearcher.com/smf/index.php/topic,60200.0.html

[E. Jensen]

I wonder how much of a yew log is "crown wood" or "juvenile" wood.  That could have a huge impact especially on fibril angle.

[wizardgoat]

I don't have too much to add, but I've for sure noticed on bows with juvenile belly wood (pith on the belly or close by), they turn out suuuuuuper good. Very little set.