Seeds

Seeds are often especially poisonous, because their destruction would thwart the plant’s reproductive strategy. Fruits, however, are bright, aromatic packets of sugars and other nutrients specifically designed to be attractive food for animals that can disperse the seeds contained in them. The seeds within the fruit are designed either to be discarded intact (like peach pits) or to pass safely through an intestinal tract (like raspberry seeds) to be deposited at some distant place surrounded by natural fertilizer. If the fruit is eaten before the seeds are ready, the whole investment is wasted, so many plants make potent poisons to discourage consumption of immature fruits, thus the proverbial stomachache caused by green apples. Nectar is like- wise designed to be eaten, but only by whatever pollinators are best for the plant that makes it. Nectar is an elaborate cocktail of sugar and dilute poisons. The recipe has evolved as an optimal trade-off between the need to repel the wrong visitors and not discourage the right ones.

Nuts represent a still different strategy. Their hard shells protect them from many animals, and some, like acorns, are also protected by high levels of tannin and other toxins. Though many acorns are eaten, some are trampled into the ground, while others are buried by squirrels and thus have a chance to sprout into new trees. It takes such elaborate processing to turn acorns into human food that we wonder if the tannin may be too much even for squirrels. Perhaps it leaches out when acorns are buried in moist soil. If so, the squirrels are processing as well as hiding their food, a neat ploy in their arms race with the oak. If you find yourself starving in an unknown wilder- ness, seek your nourishment in soft sweet fruits, the nuts with the hardest shells, and perhaps some inaccessible tubers. Avoid seem- ingly unprotected fleshy plant materials like leaves; they are much more likely to be poisonous, as they must be to protect them from your own or any other hungry mouth.