Plants with xeromorphic leaves (xerophytes) are adapted to a dry atmosphere. They are designed to prevent water loss. These characteristics are largely independent from the availability of water in the soil; they depend mainly on a low air humidity. Characteristic is: a thick cuticle, a several-layered epidermis with few stomata, constrained to the lower epidermis. Additional adaptations to prevent water loss are the occurence of hairs and invaginated portions of the epidermis protecting the stomata (cryptomeric stomata). Sometimes, other cells but the guard cells partake in opening and closing of the stomata. In some species, a "double door" system has evolved.
See below examples of leaves of xeromorphic plants: angiosperms like Rose bay (Nerium oleander) and Privy (privet), and gymnosperms like the Pine tree.
Xeromorph Angiosperms: Rose bay
Cross-section through the leaf of Rose bay (Oleander): 1 cuticle, 2 ipperepidermis, 3 palisade parenchyma, 4 spongy parenchyma, 5 intercellular space in spongy parenchyma, 6 small vascular bundle, 7 lower epidermis, 8 vacity, 9 hairs, 10 stoma
Xeromorph Angiosperms
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Rose bay
Upper and lower side leaf
Overview cross section leaf
Detail upper part leaf
Detail of cavity with hairs
Privy
Privy shrub
Close-up leaves
Upper side leaf
Lower side leaf
View of a cross section
Close-up of a cross section
Close-up with stomata
Xeromorph Gymnosperm: Example - pine
View of a cross sectioned needle
Close-up of a resin duct
Surface of the needle
close-up of stomata
Not only some Angiosperms (see two examples here above below: Rose bay (Nerium oleander; habitus here left) and privy (privet)) belong to the xeromorphic plants, but also needle-bearing Gymnosperms (Example below: pine tree, Pinus sylvestris; needles and cones here left). Like in the leaves of monocots (belonging to the angiosperms - anthophyta or flowering plants) the stomata are arranged in long arrays in pine needles.
