CLIMBING. PLANTS 119 
tion is taken over by the stipules, which are large and 
leaf-like. 
(ii.) Stipules.—In Smilax (sarsaparilla), a climber fre- 
quently seen in greenhouses, the tendrils are in the posi- 
tion of stipules. Climbing hooks may also be present. 
(iii.) Leaf-Tips.—In the climbing lily (Gloriosa superba), 
another foreign greenhouse-plant, the tips of the leaves 
are prolonged into strong cord-like tendrils. 
(iv.) Petioles—The garden-nasturtium (T'ropeolum 
majus) and Clematis have sensitive leaf-stalks. On reach- 
ing a support, they curve round it, and then become 
tough and indurated, thus enclosing it 
firmly. 
4. Root-Climbers.— These climb by 
adventitious roots, which arise in great 
number on the shaded side of the stem. 
They act as suckers, pinning the branches 
to the wall or to the tree up which the 
plant climbs—e.g., ivy (Hedera Helix). 
No suckers, however, occur on the 
flowering shoots, which turn away from 
the wall and grow outwards towards the 
light. 
In many plants the morphological 
nature of the tendril is doubtful. In the 
vegetable-marrow (Cucurbita), cucumber 
(Cucumis), white bryony (Bryonia dioica), 
Fic. 37.—StTeEm- 
and other Cucurbitacee, the tendrils have ““taxpans or 
been variously described as modified Ampelopsis 
leaves, stipules, shoots, and even roots. Veitchit, sHow- 
ING SUCKERS. 
It is possible, however, that in these (REDUCED.) 
cases the tendrils are not modified forms 
of other organs at all, but are organs, sui generis (Latin, 
of their own kind)—that is, organs which have arisen 
and have been developed for the purpose which they 
serve, never having been anything else but what they are. 
Climbing plants begin their existence as deep-shade 
plants, the shade being produced by the vegetation upon 
which they climb. In the Tropics most are inhabitants 
of forests ; in this country they are found in thickets and 
hedges. Here the partial light produces effects which 
are ordinarily associated with plants grown in darkness. 
Such plants have a long weedy appearance, with weak 
