Download Flowering Plant Vegetative Structures

Flowering Plant Vegetative Structures
BIOL 1108
I. Primary Tissues
Unlike animals, most plants have indeterminate growth, meaning that they grow throughout life.
Primary growth increases the length of stems and roots and produces the plant’s three primary tissue
types: epidermal, ground, and vascular tissue. Epidermal tissue consists of a single layer of cells that
covers plant surfaces. Ground tissue makes up most of the plant body; its functions include storage and
photosynthesis. Vascular tissue functions in support and transport. It includes xylem, which transports
water, and phloem, which transports sugars and other organics.
Plant tissues arise from undifferentiated meristem tissue that persists throughout the plant’s life.
Apical meristems are found at the tips of roots and stems and produce primary growth.
Examine the following specimens and slides available in the lab and identify the tissues and structures
mentioned. Useful figures from the textbook (Freeman, 6th ed.) are shown in parentheses.
A. Root Structure
Roots anchor plants in the soil, absorb water and nutrients, and store various plant products.
Using your textbook, identify the function of the following root structures:
epidermis
root hairs
root cap
apical meristem
cortex
vascular cylinder

Examine the monocot and dicot roots on display. Notice that dicots typically have long, vertical
taproots, while monocots have fibrous root systems.

Look at the prepared slide of a longitudinal section of onion (Allium) root and identify the
following structures: root cap, apical meristem, epidermis. (see Figure 34.16b, p. 719 and Figure
34.18a, p. 720) Can you see any root hairs?

Look at the prepared slide of a cross section of buttercup (Ranunculus) root and identify the
following structures: epidermis, cortex, vascular cylinder. (see Figure 35.6, p. 732)
B. Stem Structure
Stems support the leaves of the plant, store various products, and contain vascular tissue for
transporting water and nutrients between the roots and leaves.
Using your textbook, identify the function of the following stem structures:
node
internode
apical bud
lateral (axillary) bud
cuticle
cortex
pith
vascular bundle

Examine the Coleus plant on display and identify the following structures: stem, node,
internode, apical bud, lateral (axillary) bud (see Figure 34.1, p. 705).

Look at the prepared slide of a longitudinal section of a Coleus stem and identify the following
structures: apical meristem at tip of shoot and lateral buds (bud primordium), immature leaves
(leaf primordium). (see Figure 34.16a, p. 719)

Look at the prepared slide of a cross section of an alfalfa (Medicago) stem and identify the
following structures: epidermis, cuticle (if visible), cortex, pith, vascular bundles. (see Figure
34.19a, p. 721).
What differences do you notice between stem and root structure?
C. Leaf Structure
The primary function of leaves is photosynthesis. Leaves do not have apical meristems. Using your
textbook, identify the function of the following leaf structures:
blade
petiole
stomata
guard cells
mesophyll
vein

Examine the Coleus plant and identify the blade and petiole of a leaf.

Look at the prepared slide of a mature lilac (Syringa) leaf and compare it to the leaf model in the
lab. Identify the following structures: epidermis, cuticle, stomata, guard cells, veins. Note the
arrangement of the mesophyll cells. The layers of elongated cells on the upper part of the leaf
make up the palisade mesophyll. The more loosely arranged cell layer is the spongy mesophyll.
It contains air spaces for O2 and CO2 circulation.

Look at the demo slide of the underside of a Tradescantia leaf and identify the stomata. Are
they open or closed?
II. Secondary Growth
In addition to primary growth some plants experience secondary growth, which increases the thickness
of stems and roots. Secondary growth produces secondary xylem, or wood, and secondary phloem,
which forms the inner layer of bark. Both of these tissues are formed from a meristem tissue called the
vascular cambium, which is located between the layers of secondary xylem and phloem. Typically, new
layers of secondary xylem and phloem are produced during each growing season. The secondary xylem
persists, producing growth rings in the wood.

Look at the prepared slide of a cross section of a basswood (Tilia) stem. Identify the pith,
secondary xylem, vascular cambium, and secondary phloem. (see Figure 34.20, p. 722)
How many annual rings of wood are present? How old was this plant?