708 CLIMBING PLANTS. 



they grow out, elongate, and produce lateral branches, as may be seen in fig. 170. 

 Under favourable conditions, i.e. when these swaying shoots reach an unoccupied 

 support and become permanently attached there by their scandent roots, these 

 anchoring shoots exhibit a marked change of habit. They give rise to vigorous 

 and compact shoots with simple leaves destitute of claws, and may unfold flowers 

 and ripen fruit. In due time, when the space has become occupied, pendent shoots 

 are again produced which explore the neighbourhood for a new anchorage in the 

 manner already described. 



The group of root-climbers as a whole undoubtedly presents many points 

 of resemblance to forms with stems prostrate on the ground. The climbing 

 stems of Ivy remind one of the stems of Periwinkle, the climbing stems of species 

 of PotJios of the creeping stems of the Snake-root (Galla jjcdustris), the climbing 

 stems of Tecovia radicans of the runners of strawberry plants. The only real 

 difierence is that in one case the substratum is the surface of the soil, while in 

 that of climbing stems it is the abruptly-ascending surface of rocks and tree- 

 trunks. And this distinction is wanting in the Ivy. Ivy stems which grow 

 over stony ground, fix on to the horizontal blocks of stone by climbing roots 

 exactly as on vertical walls of rock. If mould is present in the crevices of 

 these stone blocks, the climbing roots become true absorbent roots, not only 

 fastening the stem to its substratum, but also taking up food. But ivy stems 

 cUmbing up steep rocky walls also behave in this way. The roots which proceed 

 from the portions of the stem growing over the bare stone wall are climbing 

 roots, but as soon as the stem in its growth comes to a crevice filled with earth, 

 the roots developing at that point become absorbent like those which it produces 

 when creeping on the ground. 



Thus it is clearly impossible to draw a sharp line between climbing and 

 creeping stems. Similarly, on the other hand, there are some climbing stems 

 transitional between this condition and an erect habit. Ivy, Tecoma radicans, 

 the climbing species of Ficus, even several tropical aroids, and the Brazilian 

 Marcgravia umbellata, exhibit this peculiarity. In the last-named, so soon 

 as it has climbed up a tree-trunk or steep rocky wall into an illuminated place, 

 it alters its growth completely. The shoots now formed up above no longer 

 avoid the light; they no longer develop climbing roots for attachment to the 

 substratum, their wood becomes more extensive, the hard bast surrounding the 

 wood is much more strongly developed, the shoots now not only stand erect 

 without support, but are even able to withstand flexion, and develop flowers 

 with abundant honey and ripe fruits. The erect shoots of Ivy and of the 

 climbing species of Ficus, bathed in sunshine, also unfold foliage-leaves, which 

 are strikingly different from those of the climbing shoots in size and shape, 

 and even in their internal structure. Anyone knowing only the long fila- 

 mentous shoots of Ficus stipulaia, used for covering the walls in green-houses, 

 happening to see the vigorous shoots of this plant with large leaves and figs, 

 would think it impossible that both should belong to one and the same plant. 



