Page 158 - Ultimate Visual Dictionary (DK)

PLANTS

Dryland plants STEM SUCCULENT
Golden barrel cactus
(Echinocactus grusonii)
DRYLAND PLANTS (XEROPHYTES) are able to Areole Trichome
survive in unfavorable habitats. All are found (modified (hair) Spine
lateral shoot) (modified
in places where little water is available; some
leaf)
live in high temperatures that cause excessive
loss of water from the leaves. Xerophytes
show a number of adaptations to dry
conditions; these include reduced leaf area,
LEAF
SUCCULENT rolled leaves, sunken stomata, hairs,
Lithops sp.
spines, and thick cuticles. One group,
succulent plants, stores water in specially
enlarged spongy tissues found in leaves, roots,
or stems. Leaf succulents have enlarged, fleshy,
water-storing leaves. Root succulents have a
large, underground water-storage organ with
short-lived stems and leaves above ground. Stem
succulents are represented by the cacti (family
Cactaceae). Cacti stems are fleshy, green, and
photosynthetic; they are typically ribbed or
covered by tubercles in rows, with leaves
being reduced to spines or entirely absent.
Waxy cuticle
(waterproof
Spine covering) Water-storing
(modified
parenchyma Tubercle
leaf)
(packing tissue) (projection
from stem
Sinuous surface)
(wavy)
Tubercle
cell wall Vascular
(projection cylinder
from stem (transport
surface)
tissue)
Stoma (pore)
Root
controlling
exchange of
gases
EXTERNAL VIEW MICROGRAPH OF STEM SURFACE
Spine
(modified
leaf)
Root
Areole
(modified
Tubercle
lateral shoot)
(projection from
stem surface)

Waxy cuticle
(waterproof
covering)
LONGITUDINAL SECTION
DETAIL OF STEM SURFACE THROUGH STEM
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