The Science of Plant Growing 55 



are the first to suffer. Then when growth recommences in spring the dead 

 buds are thrown off, if not before. Camellias suffer in the same way, in 

 conjunction with fluctuations of temperature. If a period of dry weather 

 succeeds the transplanting of Hollies, Laurel-cherries, Conifers, and other 

 evergreen subjects in winter they often get killed, thus proving that the 

 leaves give off more water from their surfaces than the mutilated roots can 



o 



supply. 



Bleeding*. If a Vine rod is cut into the wood in spring, before the 

 expansion of the leaves, it will bleed strongly for many days, and may even 

 die or become so weak as to be useless. Its tissues are gorged with watery 

 fluid containing a considerable amount of liquid plant food, dissolved by the 

 water from cells where it was stored. Root pressure is very strong at this 

 period, and the vessels of the wood of the Vine are very large. Much of 

 the stored food is thus lost, as well as the pressure of sap necessary to start 

 the dormant buds into fresh growth. If a Vine is cut in June or July, 

 when in full leaf, it will not bleed, because the vessels are then filled with 

 air, as a result of the transpiration current. Inarching of Vines should not 

 be attempted till they are fairly into leaf, for these reasons. If pruning 

 is accomplished in autumn, before the wood is perfectly ripened, Vines often 

 bleed in spring when root pressure becomes strong. This phenomenon of 

 bleeding, when cut in spring, may be observed in various other plants, 

 including the Birch and Maple. The former will bleed at a considerable 

 height from the ground (12 to 15 ft.), though most strongly near the base 

 of the trunk. Sugar is extracted from the sap of the Sugar Maple, and 

 Rubber from the sap of various Rubber Trees. [j. F.] 



8. MODES OF GROWTH AND VEGETATIVE 

 REPRODUCTION 



Monopodial and Sympodial Stems. When a seedling of a shrub or 

 tree has completed its first year's growth, it usually terminates in a bud, 

 covered with scales. If, on the resumption of growth next spring, this bud 

 continues the growth of the stem or axis, the latter would be monopodial, 

 and would continue to be so from year to year, so long as this order of 

 growth is maintained. The Conifers are good examples of monopodial 

 stems, particularly the species of Pinus, Abies. Picea, Sequoia, and Arau- 

 caria. If the leaders of such trees get broken, or eaten off by animals, or 

 killed by frost, they rarely recover themselves by the production of a new, 

 upright axis. Araucaria excelsa is a rare exception to this rule. If the 

 leader is cut off for the purpose of propagation, one or more upright shoots 

 on the old stock will result, and these may be utilized in the same way. 

 The side branches are useless, because they do not grow into true tree 

 shape, even though they produce roots. The side branches are secondary 

 monopodia, continued by growth at the apex, but they always retain the 

 same relation to the primary axis. Trees of this character may often be 



