ADVENTITIOUS BUDS. —PROLIFEROUS LEAVES, 111 
lopment of many of the buds of the leaves forming a spire, 
which is followed by the development of the buds in the axils of 
other leaves successively ; and as such leaves are thickly placed, 
we are unable, after the development of the branches, to trace 
clearly the turns of the spire, so that they appear to grow in a 
circle. 
- 2. Adventitious Buds.—These have been found on various 
parts of the plant, as on the root, the woody part of the stem, 
the leaves, and other organs. Thus, when a tree is pollarded, 
that is, when the main branches and the apex of the trunk are 
Bre. 217. Fig. 218. 
~ 
Fig. 217. Leaf of Bryophyllum calycinum with buds on its margins.—— Fig, 218. 
End of the leaf of Malaxis paludosa, with buds, b, b, on its margins, 
cut off, the latter becomes so gorged with sap that a multitude 
of adventitious buds are formed from which branches are deve- 
loped. The branches thus produced by pollarding are, however, 
to a certain extent, also caused by the development of regular 
buds which had become latent from some cause having hitherto 
interfered with their growth. 
In every instance the adventitious buds, like the normal 
ones, take their origin from parenchymatous tissue. Thus, if pro- 
duced on the stem or branches, they come from 
the ends of the medullary rays; or when de- Fie. 219. 
veloped upon leaves, they may arise from their 
margins, as in Malaxis paludosa (fig. 218, b, b), 
and Bryophyllum calycinum ( fig. 217) ; or from 
their surface, as in Ornithogalum thyrsoidewm 
(fig. 219, b, b, b). Leaves thus bearing buds 
are called proliferous. Such buds are naturally 
formed on the leaves of the above-named 
plants, and occasionally on others ; but they 
may also be produced artificially on various /¥. 219. A portion 
leaves, such as those of species of Gesnera, ivi Togdeindl. thie: 
Gloxinia, and Achimenes, by the infliction of — soideum, showing 
wounds, and then afterwards placing them in Die ee ee 
a moist soil, and exposing them to the other 
influences which are favourable for the growth of buds. The 
buds developed on the leaves, in such cases, ultimately form inde- 
pendent plants, and this process is therefore constantly resorted 
to by gardeners as a means of propagation. These adventitious 
