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I've created a pine tree that stabs its needles into people. Here's the way I did so:

Using genetic engineering, my fictional scientists inserted keratin-producing genes into a pine tree (gymnosperm, a clade of plants that while fruitless have complex reproductive systems and vascular tissue) embryo. Through some more work, they produced a tree that has a unique trunk.

As the meristem growth causes cork and vascular cambium to form, plant cells near the vascular bundles grow very close to the skin of the tree (near the outer ring of vascular tissue and cork cambium) and begin to elongate due to the plant hormone auxin, which stimulates elongation of cell walls without triggering cell division. As they stretch, they grow bundles of myosin. Then they produce actin filaments to power what is essentially muscle movement. These cells grow into "muscle" fibers and small threads of tissue that, while not as complex as human muscle (which has tissue bundles held together by connective tissues such as epimysium) are capable of exerting significant pressure. They grow underneath the developing quill.

The keratin plates, in the meantime, grow out of the developing muscular bundle and form a quill, like that of a porcupine . . . with two differences: the quills are stiffer, and they are pure keratin, like very fine, sharp claws. (A porcupine pine tree!)

When you go to touch the tree or tap one of the needles now embedded (point facing out) in the trunk, the muscles react to the pressure and force the needle(s) forward.

The quill is finely barbed, since according to Science, barbed quills required approximately half the penetration force of the barbless quills, or 56% of the pressure of a hypodermic needle to breach (human) skin.

From what I was able to gather, the pressure needed for a hypodermic needle to break through skin is 20 kPa (kilopascals). 56% of 20 is 11.2, so taking pressure as P, F as force, and A as area of surface on contact, $$P=\frac{F}{A}$$.

The area of my porcupine quills is exactly 1mm² at the tip. The pressure exerted needs to be sufficient to break through skin, so using this calcuator to reverse-engineer the equation, I need exactly .0112 Newtons of force to generate the pressure needed (for the tip.) That doesn't seem like too much for the muscles in the trunk to push the quill forward. I think that the defense (stabby needles) works, but I'm not sure:

The Question

Reality-check my system, please. Would the defense realistically work, or did I miss something/are my numbers wrong?

Bonus points for: telling me whether I should make the needles sharper, thicker, or thinner/pointier to make the tree more effective.

Thanks to those in the Sandbox for checking my numbers and providing a little feedback.

posted over 6 years ago

FoxElemental‭

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