Modification of Leaf

While a leaf's main job is photosynthesis, many leaves are modified for other specialised functions. Leaf tendrils form when a plant's stem is too weak to stand alone, so part or all of a leaf becomes a slender, wiry, coiling tendril that helps it climb: the entire leaf in Lathyrus, the stipules in Smilax, the terminal leaflet in Naravelia, the leaf tip in Gloriosa, the apical leaflet in Pisum, and the petiole in Clematis. Leaf hooks form when leaves turn into hook-like climbing structures - in Bignonia unguis-cati ('cat's claw creeper') the terminal leaflets become three sharp, stiff, curved hooks that grip bark like a cat's claws, and Asparagus's leaf spines act the same way. Leaf spines and prickles are sharp defensive/water-conserving structures: spines are true leaf (or stipule) modifications seen on the surface or margins as an adaptation to herbivory and dry conditions (Argemone mexicana, Solanum trilobatum, Solanum virginianum; in xerophytes like Opuntia and Euphorbia the leaves and stipules turn to spines), whereas prickles are small, sharp outgrowths of the epidermis of the stem or leaf (not true leaf/stem tissue) that help a plant scramble over others and deter herbivores (Rosa, Rubus). Storage leaves are fleshy, swollen leaves of saline/xerophytic plants and the family Crassulaceae that store water, mucilage or food and resist drying out (Aloe, Agave, Bryophyllum, Kalanchoe, Sedum, Sueada, Brassica oleracea var. capitata/cabbage). A phyllode is a flat, green, leaf-like modification of the petiole or rachis that takes over photosynthesis once the true leaflets/lamina are highly reduced or shed (Acacia auriculiformis, Parkinsonia). In pitcher plants (Nepenthes, Sarracenia) the leaf's basal part stays laminar while the midrib continues as a coiled, tendril-like structure, and the apical part becomes a pitcher whose mouth is closed by a lid formed from the leaf apex. In the bladderwort Utricularia, a rootless, free-floating or partly submerged aquatic plant, parts of the much-segmented leaf form bladder-like traps with a trap-door …