Download 21.3 Roots and Stems

21.3 Roots and Stems
KEY CONCEPT
Roots and stems form the support system of vascular
plants.
21.3 Roots and Stems
Roots anchor plants and absorb mineral nutrients from
soil.
• Roots provide many
functions.
– support the plant
– absorb, transport,
and store nutrients
– root hairs help
absorption
21.3 Roots and Stems
• There are several parts of a root.
– root cap covers the tip
root cap
21.3 Roots and Stems
• There are several parts of a root.
– root cap covers the tip
– apical meristem is an area
of growth
apical meristem
21.3 Roots and Stems
• There are several parts of a root.
– root cap covers the tip
– apical meristem is an area
of growth
– vascular cylinder contains
xylem and phloem
vascular cylinder
21.3 Roots and Stems
• There are two main types of roots.
– Fibrous root systems have fine branches.
– Taproot systems have one main root.
Fibrous root
Taproot
21.3 Roots and Stems
Stems support plants, transport materials, and provide
storage.
• Stems have many functions.
– support leaves and flowers
– house most of the vascular system
– store water
Baobab trees
Cactus
21.3 Roots and Stems
Stems support plants, transport materials, and provide
storage.
• Stems have many functions.
– support leaves and flowers
– house most of the vascular system
– store water
– grow underground for storage
Ginger rhizomes
Potato tubers
21.3 Roots and Stems
Stems support plants, transport materials, and provide
storage.
• Stems have many functions.
– support leaves and flowers
– house most of the vascular system
– store water
– grow underground for storage
– form new plants
Strawberry
stolons
21.3 Roots and Stems
• Some stems are herbaceous and conduct photosynthesis.
21.3 Roots and Stems
• Some stems can be woody,
and form protective bark.
21.3 Roots and Stems
• Primary growth increases a plant’s length.
• Secondary growth increases a plant’s width.
21.3 Roots and Stems
• Tree rings help determine the age of a tree.
bark
bands
heartwood
one year
of growth
sapwood
21.3 Roots and Stems
Root hairs anchor plants and help them absorb water
and minerals by
A.
B.
C.
D.
Protecting the growing part of the root
Producing more xylem and phloem
Increasing the root’s surface area
Lengthening the tips of roots
21.3 Roots and Stems
Where is the vascular cylinder of a root?
A.
B.
C.
D.
Covering the tip
Just behind the root cap
In the center of the root
Inside the meristem
21.3 Roots and Stems
What are the two basic forms of roots?
A.
B.
C.
D.
Fibrous roots and taproots
Long taproots and short taproots
Fine-branched roots and thick-branched roots
Vascular cylinders and meristems
21.3 Roots and Stems
Divisions of a plant’s apical meristem cells produces
A.
B.
C.
D.
Primary growth
Secondary growth
Ring growth
Lateral meristem growth
21.3 Roots and Stems
What can you infer from a thick annual ring inside a thin
annual ring in a tree trunk?
A.
B.
C.
D.
Low precipitation followed by high precipitation
A short ring followed by a very cold winter
secondary growth followed by primary growth
Good conditions followed by harsher conditions