16, 17.] TEEM OK PEKIOD OF PLANT LIFE. 2 1 



tire life is limited to a single season. It germinates 

 from the seed in Spring, attains its growth, blossoms, 

 bears fruit, and dies in Autumn ; as the Flax, Corn, 

 Morning-glory. 



41. A biennial herb () is a plant which germi- 

 nates and vegetates, bearing leaves only the first 

 season, blossoms, bears fruit, and dies the second ; as 

 the Beet and Turnip. Wheat, Rye, etc., are annual 

 plants ; but when sown in Autumn, the sudden frost 

 prevents flowering, and they become biennials. 



42. Monocarpic herbs. The Century-plant (Agave), the Talipot-palm, etc., are 

 so called. They vegetate, bearing leaves only, for many years, accumulating 

 materials and strength for one mighty effort in fructification, which being 

 accomplished, they die. In some species the term of life depends on climate 

 alone. The Castor-bean (Ridnus) is an annual herb in the Northern States, 

 a shrub in the Southern, and a tree of large size in its native India. So 

 Petunia, annual in our gardens, is perennial at home (in Brazil). 



43. Perennial plants are such as have an indefinite 

 duration of life, usually of many years. They may be 

 either herbaceous or woody. Herbaceous perennials, or 

 perennial herbs (2), are plants whose parts are annual 

 above ground and perennial below. In other words, 

 their roots or subterranean stems live from year to 

 year, sending up annually, in Spring, flowering shoots 

 which perish after they have ripened their fruit in 

 Autumn ; as the Lily, Dandelion, Hop. 



44. Woody perennials usually vegetate several years, 

 and attain well-nigh their ordinary stature before flow- 

 ering ; thenceforward they fructify annually, resting or 

 sleeping in winter. They are known as trees (b), 

 shrubs (b), bushes, and undershrubs (b) distinctions 

 founded on size alone. 



45. A shrub (b), is a diminutive tree, limited to 

 eighteen or twenty feet in stature, and generally divid- 



