Plants with spines: this term is used here in a very broad sense, for all plants which have prickly or thorny, more or less stinging structures:

True thorns derive from the transformation of the tip of branches, such as in several species of Rhamnus or Crataegus:
Spines derive instead from the modification of the stipules, such as in the genus Berberis

The prickles found in the genera Rosa and Rubus are extensions of the cortex and epidermis:

The term spine is also used for those found along the margins of leaves, which derive from the thickening of the leaf-teeth:

A similar case are the cladodes of some species of Ruscus and Asparagus, which may become rigid and stinging:

Different is the case of the genus Opuntia in which the 'spines' may derive from the transformation of an entire leaf or from spine-like hairs called glochids:

In several species of the Asteraceae family the spines may be present both along the margins of leaves and on the bracts surrounding the inflorescences (heads), which are also modified leaves, such as in the genus Carlina...:

...or in many species of thistles:

Non spiny-plants are devoid of thorns, spines, prickles or any other stinging structures on stems and leaves.