Ginseng

Ginseng is a consumable item in the, first introduced in Golden Sun: Dark Dawn. Like most consumable items, each party member can hold up to 30 ginseng in a single inventory slot. When used, ginseng restores 50 Psynergy Points to a single party member. Ginseng can be bought for 600 coins and sold for 450 coins.

Dark Dawn Ginseng
In Golden Sun: Dark Dawn, Ginseng can be bought from the item vendor in Tonfon.

One can also be found in Crossbone Isle.

Analysis
The first thing worth noting is that Adepts automatically recover PP as they walk through dungeons or across the world map, making ginseng useful only during battles. That being said, the practicality of ginseng depends largely on a player's preferred style of combat. Those who cast Psynergy spells often will want to stock up on as much ginseng as is reasonably possible. On the other hand, players who are more conservative with their Psynergy, instead opting for physical attacks, Djinn, and other consumable items, would be better off investing their money in stronger equipment and more healing items like vials and antidotes.

Further reducing the value of ginseng is that, due to appearing late in a game, players will likely have found other PP-restoring alternatives. Djinn such as Ether can restore PP with relatively little cost, and armor such as the Lucky Cap and Mythril Circlet will restore a few Psynergy Points at the end of each turn. The main drawbacks of these methods is that PP-restoring equipment is typically slow-acting, and there aren't enough PP-replenishing Djinn for every Adept to have one. Ginseng solves both of these problems, as it can be used by any party member and restores enough PP at once for several more Psynergy spells.

Unlike Hit Points, the consequences for running out of Psynergy Points are fairly mild. A character without any PP can still perform physical attacks, use items, unleash Djinn, and pretty much any other battle command except casting Psynergy. Also, PP can be restored through normal means even if a character has zero Psynergy Points remaining. These lax punishments, coupled with ginseng's high price, should compel players to conserve ginseng for situations where a character is almost out of PP. Also, if a player has very little ginseng available, they should be saved for when that character has a Psynergy spell that would provide a strategic advantage.

Ginseng is perhaps best reserved for boss battles. The most obvious reason is that boss battles take longer than normal battles, putting a larger strain on a party's PP reserves. Another, less-obvious reason is that single-target Attack-based Psynergies like Odyssey and Vicious Chop are a simple and common strategy for defeating bosses faster. Unfortunately, such Psynergies are usually learned by classes with low PP totals, putting an even greater strain on those characters' PP pools. Should these characters run out of PP while a boss is still standing, a couple of ginseng may provide just the boost needed to win.

As mentioned earlier, there are many other ways to restore PP in the Golden Sun series. As far as consumable items are concerned, however, ginseng is neither the best nor the worst choice, although it does have its advantages over other items. Khiren water is more cost-effective than ginseng, but near the end of a game the ability to replenish more Psynergy Points at once is typically worth the extra cost. Psy crystals, on the other hand, are far more effective than ginseng. However, the removal of certain minigames have made Psy crystals harder to come by. Ginseng, on the other hand, can be bought in limitless quantities (or at least until players can't carry any more), making them a new staple in end-game inventories.

Trivia

 * Ginseng is tied with dream leaves for the position of most expensive non-Artifact consumable item.