abeka biology 10 section 4.2

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1. bark
2. wood
3. pith

what are the three areas that a woody dicot stem easily divides into?

xylem

plant vascular tissue that transports water and dissolved minerals upward from the roots to the leaves

vascular cambium

a layer of meristematic tissue that produces new bark and new xylem and is responsible for the secondary growth of woody stems

pith

the soft tissue at the center of young stems

bark

the outer section of a woody stem

epidermis

outermost layer of the bark

cork

plant structural tissue that forms the bark of woody plants

cortex

young woody stems have a second layer of tissue underneath the epidermis which stores food for the stem

lenticels

allow the tissues in the stem to obtain necessary oxygen from the air

phloem

innermost layer of the bark; carries sugars and other foods made in the leaves downward to the growing parts of the stem and roots

sieve plates

perforated plates

sieve tubes

which conduct food throughout the plant

companion cells

strengthen the phloem tissue

vascular cambium

cambium tissue that produces new vascular tissue

girdling

the technique of girdling removes a ring of bark and vascular cambium from a tree trunk

wood

*strong, resilient inner section of a woody stem*; provides strength and support for the stem and helps transport water and minerals from the roots to the leaves

xylem

the tissues that conduct sap upward from the roots to the leaves

conifers

cone-bearing trees

tracheids

long, narrow, rod-shaped cells that often have tapered ends and helps conduct water in the xylem of a woody stem

broadleaf trees

contain tracheids that give strength to the tree and conduct water from the roots to the leaves

vessels

large water-conducting tube in the xylem of a woody stem

vascular tissue

forms the circulatory system of the plant

vascular rays

radiate outward from the center of the trunk like the spokes of a bicycle wheel

resin ducts

special tubes lined with resin-producing cells

pith

the center of a woody stem in a young plant

water

**fill in the blank**

pith cells are packed loosely together and function mostly as _____ storage cells

heartwood

inner portion of a woody stem, made of older xylem tubes that have become clogged and been sealed off

sapwood

younger, functioning xylem tissue found in the outer portion of a woody stem

lighter

**fill in the blank**

sapwood is usually _____ in color than the heartwood

secondary growth

growth of a stem in width

annual growth rings

distinct layer in the xylem of a woody stem formed by annual variation in the rate of secondary growth

singular

**fill in the blank**

one layer of spring and summer wood taken together makes up a _____ annual growth ring

grain

light and dark streaks in wood formed by differences in the size of springwood and summerwood vessels