Page:An introduction to physiological and systematical botany (1st edition).djvu/133

 Rh the body of the Root, and Radicula the fibre. The latter only is essential, being the part which imbibes nourishment.

Roots are either of annual, biennial or perennial duration. The first belong to plants which live only one year, or rather one summer, as Barley; the second to such as are produced one season, and, living through the ensuing winter, produce flowers and fruit the following summer, as Wheat; and the third to those which live and blossom through many succeeding seasons to an indefinite period, as trees, and many herbaceous plants. The term biennial is applied to any plant that is produced one year and flowers another, provided it flowers but once, whether that event takes place the second year, as usual, or whether, from unfavourable circumstances, it may happen to be deferred to any future time. This is often the case with the Lavatera arborea, Tree Mallow, and some other plants, especially when growing out of their natural soil or station. Linnæus justly observes that however hardy with respect to cold such plants may prove before they blossom, they perish at the first