388 LESSONS WITS PLANTS 



492a. Plants which are widely cultivated generally develop varie- 

 ties of different durations; and some perennial plants, as tomato and 

 red pepper, have varieties which are almost true annuals in northern 

 countries. Plants which were originally presumably annuals have been 

 developed into potential biennials, as radish and turnip ; and on the 

 other hand, the perennial sea-beet is considered to be the parent 

 of the potentially biennial garden beet. 



493. Both bleeding- hearts and lilacs are peren- 

 nials, but one dies to the ground every fall and 

 the other does not. Moreover, the bleeding-heart 

 becomes weak in a few years and dies out, but 

 the lilac retains its vigor year after year. Even 

 perennials, then, may not live always ; and there 

 are characteristic differences in their duration. 

 Plants which remain soft and non- woody are herbs. 

 The bleeding-heart, — and every perennial which 

 dies to the ground in the fall, — is an herbaceous 

 perennial. 



493o. The horticulturist is well aware that perennial plants may 

 have only a short span of life ; else why does he "renew" his beds 

 of grass- pinks, columbines, bluebells, hollyhocks, hardy chrysanthe- 

 mums, and the like, after they have flowered two or three years? 



4936. Flowers which are technically known as annuals among 

 gardeners may be annuals or plur-annuals, or biennials, or even per- 

 ennials which bloom freely the first year from seed. 



LXXVI. THE STATURE AND HABIT OF PLANTS 



494. The cherry (Figs. 16, 17), oak, maple, 

 have a single trunk or stem, and we have seen 



