Peaches

Peaches are the same as the fruit known today, with the important exception that they are believed to be poisonous in the Third Age.

Belief in poisonous nature

All parts of the peach tree, with the exception of the edible peach fruit, contain cyanide-producing compounds that are released when peach seeds, bark, and leaves are eaten.

Both Moiraine Damodred and Pevara Tazanovni uses the phrase "as sure as peaches were poison", while Nynaeve al'Meara cites "powdered peach pit" alongside Gray fennel when talking about a poisoned blade. Nyneave calls the pit "the most poisonous part of the peach." This belief is echoed by Graendal who likens Cyndane to a peach, thinking "peaches were poisonous, here and now." The "here and now" implies that they were not poisonous in Graendal's own Age. The origin of this comes from the fact that, in our world, peaches contain chemicals called cyanogenic glycosides which, when broken down by the human body, release cyanide. This feature is also present in other fruits of the same family, such as apricots, plums, nectarines and cherries.

This is, however, contradicted by The Wheel of Time Companion which defines peach as a "fruit whose pit could be powdered and used as poison. It was widely, and erroneously, believed that the fruit itself was poison". Apparently, even Graendal followed this belief, likely never having tested one to find out. Brandon Sanderson teases this fact in the potential future seen by Rand during his final battle with the Dark One. A woman name Renel is selling peaches from Tear. Rand reacts with horror, but she reassures him by saying they "have the toxin removed" and then proceeds to eat one. She also shoots a street urchin for stealing one, which she would be unlikely to care about if they were poisonous. Her scam is not that she is selling poison, but that there is no special process for removing the toxin as they were not toxic to begin with.

The mistaken belief, like the fact peaches have poison in them, also originates from real life. Tomatoes were once referred to as "wolf peaches" and "poison apple" and were believed to be poisonous. A similar belief surrounded potatoes, which were called "the Devil's apples". With regards peaches, one rumor says that King John died from "a surfeit of peaches".

Robert Jordan and Harriet McDougal have both weighed in on this. Speaking in 2013, Harriet said:

Someone wrote and said, "When did peaches become poisonous?" And I said, "You know, they're not." One of Robert Jordan's great themes was the unreliability of information, that we all think we know things that sometimes are absolutely cuckoo, and that's one of them. We do...if a child manages to eat a peach pit, chewing on it to get at the kernel inside, then you have to call poison control. That's true now, so that's why.

Robert Jordan might, at first glance, appear to contradict this:

For Child of Lir, peaches being poisonous in the world of tWoT is one of the things I did to make the world different. Though peach pits do contain small amounts of cyanide, which was once manufactured through processing peach pits

This is, however, not incompatible with the belief that peaches are poisonous, rather than them actually being poisonous.

Other references

In his meeting with Tuon, Rand al'Thor causes a grove of peach trees to grow and flower around him using his Singing ability. According to Tuon, peach blossoms are "the most powerful omen she knew." We can assume that they are favorable as it accompanies the other sign she had been waiting for, that the Dragon kneel before the Crystal Throne.