Perennial Herb

The term Perennial was derived from two latin words, “per” (means through) and “annus” (means year). When a plant is found to live for more than 2 years, it is called a perennial plant or a perennial. This term was coined to differentiate between the short-lived annuals, biennials and others.
Life cycle

• These plants can be short-lived or can be long-lived.
• Their height may range from a few millimeters to 100 meters.
• Ranging from ferns to flowering plants (like orchid) to tree, all types of herbs can be found.
• Most of the perennials can flower for many seasons during their lifetime (polycarpic).

Growth

• These herbs have some typical structures (like bulbs, rhizomes, tubers woody crowns) that can undergo vegetative reproduction in place of seeding. This ability helps these herbs to live from one season to the next.
• Specialized stems or crowns may be present to help the plants to survive over dormancy during unfavorable conditions.
• Many perennials may produce relatively large seeds which can form larger seedlings after germination. Thus, the plant can compete more effectively with other plants and can develop leaves more quickly.
• Perennials do not need to produce more seeds, but can produce seeds for many times during their lifetime.
• Example – dahlia.

Structure

• Perennials show a constant growth during favorable conditions, which is limited during unfavorable seasons.
• The roots remain protected below ground in the soil.
• The plant is comparatively tolerant to wildfire.
• A few perennial herbs are capable of tolerating the extremities of the cold season. But are usually less sensitive than others.
• Example – Kiwi Fruit

Benefits

• Numerous benefits have been known with the perennial crops.
• These have deep-penetrating, extensive root systems and helping in the following ways -
• hold the soil better and prevent soil erosion.
• capture dissolved nitrogen before it contaminates the ground water and surface water
• reduces the need for herbicide use
• cause carbon sequestration and decrease the effect of global warming
• Example – Switchgrass (has deep roots with length more than 3 meters)

the t o  : http://herbs.ygoy.com/2010/07/18/perennial-herb/