PEEIODS OF FLOWERING. 261 



of flowering, are enabled to accumulate a greater amount of nutritive 

 matter, and thus to withstand the exhaustion. Many cultivated 

 plants which lay up a large store of nutriment in the form of starch, 

 lose it when the plants shoot out a flowering stem. This is seen in 

 the case of Carrots and Turnips, in which the succulent roots become 

 fibrous and unfit for food when the plants are allowed to run to seed. 

 The receptacle of the Artichoke and many Compositse, which is succu- 

 lent before the expansion of the flowers, becomes dry as the process of 

 flowering proceeds. The juices of plants, when required for the pur- 

 pose either of food Or medicine, ought in general to be collected 

 immediately before the flowering of the plant. 



By cutting a ring out of the bark of trees, and thus retarding the 

 descent of the sap, the period of flowering is sometimes hastened. 

 Again, when the period of flowering is long delayed, either naturally, 

 as in Agave and several palms, or artificially, the process, when it 

 does begin, proceeds with amazing rapidity and vigour. Eichard 

 mentions that a plant of Agave, which had not flowered for nearly a 

 century, sent out a flowering stem of 22|- feet in 87 days, increasing 

 at one period at the rate of one foot a day. In such cases this vigor- 

 ous flowering is often followed by the death of the plant. Common 

 fruit trees, when they begin to flower, often do so luxuriantly ; but 

 if, from the season being bad, there is a deficiency in flowering, it 

 frequently happens that, from the accumulation of nourishment, the 

 next year's produce is abundant. 



If plants are allowed to send ' out their roots very extensively in 

 highly nutritive soil, the tendency is to produce branches and leaves 

 rather than flowers. In such cases, cutting the roots or pruning the 

 young twigs may act beneficially in checking the vegetative functions. 

 In pruning, the yotmg shoot is removed, and the buds connected with 

 the branch of the previous year are left, which thus receive accumu- 

 lated nourishment. Grafting, by giving an increase of assimilated 

 matter to the scion or graft (see remarks on Fruiting), and at the 

 sarne time checking luxuriant branching, contributes to the hastening 

 of the period of flowering. 



The period of flowering of the same plant varies at difierent 

 seasons, and in different countries. During the winter, in temperate 

 climates, and during the dry season in the tropics, the vegetative pro- 

 cess is checked, more especially by the diminished supply of moisture,, 

 and the arrestment of the circulation of the sap. The assimilated 

 matter remains in a state of repose, ready to be applied to the purposes 

 of the plant when the moisture and heat again stimulate the vege- 

 table functions. This stimulation occurs at diiferent periods of the 

 year, according to the nature of the climate. By observing the 

 mode of flowering of the same species of plant in successive years, 

 conclusions may be drawn as to the nature of the seasons in a 



