REPRODUCTION— THE FLOWER, 



49 



ally plants in a state of nature, left to themselves, 

 do not flower till they have attained a certain 

 age, an age very different in different cases. A 

 so-called annual plant will flower and produce 

 seed within a few weeks of its birth, whilst 

 decades of years may pass before others are in 

 a state to produce flowers. We are often 

 content to attribute these differences to age, 

 but that of itself is, of course, no explanation 

 of the phenomenon. Gardeners in like manner 

 attribute the development of the flowers to 

 what they call ripening of the wood, and the 

 phrase, though open to objection in form, is 

 substantially true in fact. The ripening of the 

 wood in autumn implies that the season, on 

 account of its temperature more especially, has 

 been favourable for the development of the 

 tissues and for the formation and storage of 

 food-materials. A relatively high temperature, 

 together with an adequate supply of water and 

 exposure to light, have been shown to be essen- 

 tial to the growth of the seedling plant, of the 

 buds, and of the plant in general. 



For the production of flowers it is generally 

 observed that the quantity of water supplied 

 should be lessened and the temperature in- 

 creased. Many plants refuse to flower in this 

 country, simply because they do not get enough 

 heat, or a sufficiently long exposure to a high 

 temperature and a bright light. Transfer these 

 same plants to another climate, where heat and 

 light are more abundant, and flowers will be 

 produced. In this country we can, by means 

 of glass-houses and hot-water apparatus, regulate 

 the amount of water and of heat, but hitherto 

 we have not been so successful in simultaneously 

 adjusting the intensity of the light. The electric 

 light, though at present too costly to be intro- 

 duced into general practice, will eventually, no 

 doubt, remedy this state of things, as it has 

 been demonstrated that under its influence 

 plants grow and fruits ripen with extraordinary 

 rapidity. A time will come when experienced 

 gardeners will be as well able to manage the 

 lighting of their houses as they do now the 

 heating, the water-supply, the shading, or the 

 ventilation. Under existing circumstances, a 

 period of rest or of diminished activity is 

 desirable. Partly this is accomplished by the 

 alternations of light and darkness, but more 

 particularly by the diminution in the amount 

 of heat and light, to which plants in the 

 open are subject in winter, and under glass 

 the diminished supply of water also. During 

 this resting stage it must not be supposed that 

 the plant is altogether dormant, unless, indeed, 

 Vol. I. 



the temperature is too low to allow of any 

 activity at all. On the contrary, transpiration 

 and respiration, as explained in former para- 

 graphs, are going on, and those processes neces- 

 sarily imply chemical changes which play an 

 important share in the " ripening of the wood " 

 and the formation of the flower. The methods 

 employed by gardeners to promote flowering 

 are, generally speaking, of such a nature as to 

 check growth in general, and to compel the 

 plant to turn its energies in the direction of 

 reproduction. Thus, cramping the roots in pots, 

 pruning the roots, laying the roots bare, bend- 

 ing the shoots downwards, diminishing the 

 supply of food, especially of water, concurrently 

 with a high temperature, are all means which 

 have as their basis a diminished activity in the 

 vegetative system of the plant. In the case of 

 an annual plant, there is no resting stage other 

 than that manifested by the seed, the amount 

 of sun-heat, light, and moisture being sufficient 

 to allow of the whole life-cycle being completed 

 in one season. Possibly the introduction of the 

 electric light used night and day will enable the 

 gardener to induce continuous growth and the 

 rapid completion of the flowering stage. That 

 the plant subjected to such conditions will 

 be the sooner exhausted, and die of premature 

 old age, is likely enough, but this would be no 

 disadvantage to the gardener, who could readily 

 provide for that contingency by a continuous 

 succession of reserve plants. 



The Conformation of the Flower. 



The simplest flower consists of a single stamen, 

 or of a single ovule. In the vast majority of 

 cases the arrangements are more complex, the 

 stamens are invested by one or more coverings, 

 and the ovule is invested by an ovary, and that 

 by one or more coverings like the stamen. 



Flowers are spoken of as 'unisexual when they 

 are male, $, or female, $. When a stamen or 

 stamens only occur in a flower, that flower is 

 called a male flower; when an ovary or ovaries 

 are present without stamens the flower is female. 

 When both stamens and ovules occur in the same 

 flower the flower is called hermaphrodite, and 

 marked with the sign A. It must, however, be 

 carefully borne in mind that though a flower be 

 structurally hermaphrodite, it is not necessarily 

 functionally so, the influence of pollen from an- 

 other flower being generally desirable and some- 

 times essential, as will be explained later on. 



In some cases male flowers and female flowers 

 occur together, e.g. on the Cucumber plant, which 



