Ginseng root is probably the most familiar tonic herb. There are several types of Ginseng, all of which share many characteristics.
Panax Ginseng is the most famous of the Ginsengs. It is most often available as "Red" or "White" Ginseng. (The difference between Red Ginseng and White Ginseng is how the roots are treated after harvesting.)
Panax Ginseng has a very long history as a tonic herb, going back thousands of years. The word "Panax" comes from the same root as panacea, (cure-all), and was used to describe the many, many uses of ginseng.
There is also a Siberian Ginseng. Eleutherococcus Senticosus (often called Eletheuro) may be the most researched herb on the planet. This was the first herb described as an adaptogen. (Acanthopanax Gracilistylus is also sold under the name Siberian Ginseng, and shares many properties with Eleuthero.)
A few effects of Siberian Ginseng are: increases endurance; helps insomnia; lowers blood pressure; improves blood circulation; improves blood flow to the brain. (A full listing would take several pages.)
Some herbalists say Siberian Ginseng is the safest of the Ginsengs. It is often used with elderly or infirm individuals, to improve their energy levels.
There is also an American Ginseng, Panax Quinquefolium, which once grew wild in great abundance. Over-harvesting has made wild American Ginseng scarce. Botanically, this is the closest to Panax Ginseng.
All these varieties function as adaptogens, and tonify a range of body systems. They are all safe to use, and are suitable for long term use.
Some people find that Panax Ginseng over-stimulates them, and find Siberian Ginseng to be a better choice.
All of the Ginsengs are available as raw herbs, in capsules and freeze dried powders. Capsules and powders are the easiest to use, simply follow the manufacturer's directions. Some herbalists say that using standardized extracts gives you less benefit than using the whole root.
Trying one or more of the Ginsengs is a good way to introduce yourself to the benefits of herbal tonics.