PHYSIOLOGY 301 



perfect individual may ensue. In vegetative reproduction the process 

 is similar except that the separation of the part from tBe parent plant 

 is an organic one, occurring in the natural course of development. 

 The vegetative form of reproduction is manifested in various aspects, 

 and may be distinguished as a multiplication by means of multicellular 

 vegetative bodies (buds, gemmae), or by single cells (spores). 



Multiplication by Multieellular Vegetative Bodies (Budding 1 ) 

 often consists merely in the separation of lateral shoots, or in a 

 division of a single plant into several. In this way the lateral 

 shoots of Azolla, through the death and disruption of the older 

 parts of the parent axis, become separated from one another and 

 continue their growth as independent plants ; similarly, separate 

 plants originate from the vegetative body of the Duckweed (Lemna). 



Multiplication by stolons, rhizomes, and tubers results in a similar 

 formation of independently existing plants. As may be seen in the 

 Strawberry, the Bugle (Ajuga, reptans) and numerous other plants, 

 the shoots produced from many of the axillary buds of the widely 

 outstretched stolons take root and form new plants. In cases where 

 the runners themselves eventually die, the parent plant becomes finally 

 surrounded by a colony of entirely independent plants. Instead 

 of forming runners, the single tuber may divide (Corydalis solida), 

 and in this way give rise to two, four, or more new tubers. New 

 bulbs are produced in the leaf-axils of the bud-scales of bulbs, while 

 brood buds (bulbils, gemmae) are frequently developed on aerial 

 vegetative organs. 



Bulbils are found on the inflorescence in the place of the flowers in many species 

 of Allium, in the grass Poa bulbifera, and also in Polygonum viviparum. In 

 Lilium bulbiferum, Dentaria bulbifera, etc., the bulbs in the axils of the leaves are 

 specially constructed with a view to detachment from the parent plant (Fig. 22). 

 The swollen leaves contain reserve food material, and frequently develop roots before 

 falling from the plant. In Ranunculus Ficaria the roots of the axillary buds are 

 full of reserve food material, and resemble grains of corn. When the plant dies the 

 bulbils remain on the ground, and have given rise to the fable of showers of grain. 

 Bulbils or gemmae are met with also among the Mosses, Liverworts, and Ferns. The 

 winter buds of many water plants (Hydrocharis, Utricularia, Lemna, etc.) have a 

 peculiar biological significance. They are formed in the autumn, and sink to the 

 bottom of the water ; in the succeeding spring they rise to the surface and form 

 new plants. 



By vegetative multiplication higher plants can annually give rise to individuals 

 which are strong and capable of flowering and fruiting. The seedlings of sucli 

 plants, on the other hand, often require to grow for several years before the 

 capacity of sexual reproduction is attained (bulbous plants, Hop, etc.). 



In addition to the instances just cited, in which the vegetative reproductive 

 bodies take their origin from points where lateral shoots are normally formed, they 

 may also appear in places where no shoots are normally developed. Thus the 

 adventitious formations often found on leaves, particularly on the leaf-blades, 

 serve the purpose of reproduction. Just as the leaves of Begonia, Drosero, etc.. 



