BOTANY. 349 



of course hybridize and exchange whatever properties they possess. 

 The saccharine secretions of one variety will be dim inished by hybridation 

 with another not possessed of an equal amount. And the saccharine quali- 

 ties peculiar to one may be lost by planting in a soil or climate differing 

 from that which has brought them forth in unusual quantity. If their culti- 

 vation as a forage plant, and a syrup or sugar-producing plant, shall prove 

 profitable, the use of the grain in the form of flour, as well as food for cattle 

 and poultry, may considerably diminish the cost of cultivation. 



ON THE DURATION OF THE LIFE OF PLANTS. 



The following paper was recently read before the Botanical Society of 

 Edinburgh, by Prof. Fleming : 



The phrases ordinarily employed to express the duration of life in plants 

 are annuals, biennials, and perennials. Viewing the subject, however, in refer- 

 ence to function rather than seasons, divisions much more consistent with 

 the phenomena must be resorted to. Thus, in the case of annuals, it may 

 happen, in an unfavorable season, that the plant may outlive the winter, 

 flourish during a portion of the following season, and thus become a bien- 

 nial. But in many cases those plants termed biennials merely extend them- 

 selves during the first season, and in the following flower, ripen their seeds, 

 and perish. But in both cases the plant dies after having once executed the 

 function of reproduction. Those plants have their vitality completely ex- 

 hausted by the seed-producing process, and, in consequence of this functional 

 character, they constitute a very distinct group, to which the somewhat 

 ambiguous term Monocarpous has been applied by De Candolle and Lindley. 

 It suggests the idea of the plant producing only one carpel or seed-vessel. 

 As defined by Lindley, however, it may be conveniently employed. He says : 

 " Monocarpous, bearing fruit but once, and dying after fructification, as 

 wheat. Some live but one year, and are called annuals ; the term of the 

 existence of others is prolonged to two years, these are biennials ; others 

 live for many years before they flower, but die immediately afterwards, as 

 the Agave americana." 



In proof that it is the production of the seed which consumes the vitality 

 of the plant, it will be found that by destroying the flower-buds the life of 

 the plant will be prolonged until new flower-buds be produced, or those 

 already existing but in an imperfect state become developed. Thus, I have 

 kept the common oat, Avena sativa, for four seasons by cutting off the flow- 

 ering stem. The annual bean may be easily converted into a biennial. The 

 tree mallow, Lavatera arborce, usually considered a biennial, in one case out- 

 lived the greater part of the second winter with me, but perished by the 

 severity of the frost in the spring of 18-35, having a stem displaying spurious 

 annual rings of growth, about eighteen in number, marking intermittent 

 action, irrespective of the dead or winter season, and well calculated to give 

 a salutary warning to the vegetable palaeontologist. The circumstance of 

 monocarpous plants having their life prolonged by being prevented from 

 flowering, and the production of new parts for flowering purposes, give no 

 countenance to the assertion of Knight, in his paper " On the Reproduction 

 of Buds : " " Xature appears to have denied to annual and biennial plants (at 

 least to those which have been the subject of my experiments) the power 

 which it has given to perennial plants to reproduce their buds." This charac- 

 ter of the individual plant being capable of reproduction only once, was well 



30 



