Sclerenchyma was discovered by Medeneus (1805). They have dead cells and import hardness to plant parts giving mechanical strength.
Leaves of Pinus are dimorphic, ie, two types
(i) Brown membraneous scale leaves (cataphylls) present on both long and dwarf shoots and serve to conserve water around the branches.
(ii) Green acicular needle like foliage leaves present only on dwarf shoots. These needle perform photosynthesis and do not shed even in winter.