180 Structural and Physiological Botany. 
plant, like the reproductive organs already mentioned, but 
are usually attached to definite positions, being found — 
almost exclusively in the axils of leaves. The mode of 
reproduction by buds is of the highest practical import- 
ance, and is made use of by gardeners in a great variety of 
ways, since by this means not only is the species but the 
particular variety propagated, which is not always the case 
in reproduction by seeds. ‘To this class belong repro- 
duction by bulbils, runners, cuttings, grafting, layering, and 
budding. In these processes, so different in their external 
appearance, reproduction depends simply on the further 
development of buds which have become spontaneously 
detached from the parent plant, or artificially separated 
from it. | Y 
Bulbils are endowed in a high degree with the power 
of independent life ; they become spontaneously detached 
from the parent plant, and, when they fall to the ground, 
continue to grow like seedlings. They occur especially ia) 
bulbous plants ; in the hyacinth, for example, in the axils of 
the bulb-scales (Fig. 122, p. 82), in some lilies 
| and in some species of Ad/um within the in- 
florescence. More rarely they are ‘found on 
the surface of the leaf, as in Cardamine pra- 
tensts, | Bryophyllum|, and some ferns. 
Multiplication by the division of under- 
ground [or aérial] stems, as in the Aster and 
couch-grass, Triticum repens, and by runners, 
Fic. 350.- Stem of ag in the strawberry, 1s so simple and so 
Lilium  bulbtfe- 
rum; s bulbils well known as not to require further descrip- 
developed in the 
axils of the leaves tion. 
e, While in all the cases already described | 
buds which have separated spontaneously from the plant have 
at once a power of new growth; in cuttings, grafts, layers, 
and buddings, on the other hand, the wound caused by an 
artificial and violent separation must first heal. The forma- y 
| in the axils of the foliage-leaves (Fig. 350), 
