Some kinds of touring plants send out long trailing stems to search for
fresh rooting places. A little Alpine saxifrage is curious in this
respect, for the plant will traverse over many feet of barren rock to
reach a suitable position. Directly the shoot touches the soil, a new
plant is formed, and as this grows up, the connection between it and the
parent is severed. A kind of lily has an even more singular way of
traveling about. Here, after the plant has flowered, buds arise on the
stems which bore the blossoms. Eventually they take root in fresh
positions. This plant if left alone would rapidly cover many yards with
its offspring, and this without setting a single seed.
A strange group of plants are those which actually break themselves in
pieces in order to pursue their journeys abroad. A plant belonging to
the Houseleek order (_Sempervivum soboliferum_) is remarkable in this
respect. The species naturally finds its home in the crevices of rocks,
and at a certain stage in its development numerous little ball-like
offshoots are produced. In the early days these are kept at home by the
stems by means of which they are attached to the parent plant.
Eventually these attachments shrivel up and the offshoots go rolling
away over the rocks often much helped in their journey by the wind. A
considerable distance may be traversed before a little ball finds a
resting-place in some niche.
[Illustration: =HOW THE CACTUS PROTECTS ITS FLOWERS=]