Principles of Biology
By
Frank H. Osborne, Ph. D.
Lab 6 - Green Plant II
Monocotyledonous Seed Structure
A. Monocot seeds
1. Monocot seeds have one
cotyledon.
2. The cotyledon stores food for
the embryonic plant.
3. The embryonic plant is located
next to the cotyledon.
2. Dicotyledonous
seeds
1. Dicot seeds
have two cotyledons.
2. The cotyledons
have the embryonic
plant between them.
Root Structure
A. Monocot roots
1. Monocot roots have xylem tissue scattered
in a ring.
2. Phloem tissue is scattered in a ring. It
alternates with the xylem.
3. There are very few xylem cells in each
location.
Monocot
Root
Structure
Root Structure
B. Dicot roots
1. Dicot roots have xylem tissue concentrated
in the center in a star-shaped pattern.
2. Phloem is found between the points of the
star.
3. Large numbers of xylem cells are
concentrated in the star.
Dicot Root
Structure
Stem Structure
A. Monocot stems
1. Vascular bundles are scattered in the pith.
2. Vascular bundle structure
a. a few xylem cells
b. air space
c. phloem opposite the air space
d. surrounded by sclerenchyma fibers
Monocot
Stem
Structure
Monocot
Stem
Structure
Xylem
Air Space
Phloem
Sclerenchyma
Stem Structure
B. Dicot stems
1. Xylem and phloem are concentrated in a
circle.
2. Xylem is on the inside. The phloem is on
the outside. The cambium is in between the
xylem and the phloem.
3. Larger stems have xylem in rings.
4. There are always large numbers of xylem
cells present.
Dicot stem structure
Dicot Stem Cross-section
Leaf
Structure
Leaf Structure
A. Monocot leaves
1. Monocot leaves have parallel veins
2. Each vein has only a few xylem cells.
3. Monocot xylem cells always appear
circular in cross section.
Monocot leaf structure
Leaf Structure
B. Dicot leaves
1. The veins of dicot leaves form a netted
pattern.
2. Dicot veins always have xylem on top and
phloem underneath.
3. Each vein has large numbers of xylem cells.
4. The veins do not all appear circular in
cross-section.
Dicot leaf structure
The End
Lab 6
Green Plant II