MOUNTAIN PROVINCE STATE POLYTECHNIC COLLEGE
TADIAN, CAMPUS
IN PARTIAL FULFILLMENT OF REQUIRMENT IN AGROFORESTRY SEED
TECHNOLOGY
SEED AND ITS STRUCTURE
ACTIVITY #3
1ST SEMESTER S.Y. 2023-2024
INTRODUCTION TO MONOCOT AND DICOT SEEDS
DARYL DOGUI-IS GUINAYEN
BSAF 3
OCTOBER 10, 2023
I. INTRODUCTION
Definition and types of seeds
Seed refers to the fertilized, matured ovule that contains an embryo
plant, stored material and a protective coat or coats.
A seed is a mature ovule that comprises an embryo or a miniature
undeveloped plant and food reserves, all enclosed within a protective
seed coat. Seeds are a way of reproduction for all flowering plants.
Every seed is capable of growing into a new plant under proper
environmental conditions such as the right temperature, moisture
and sunlight.
The seeds of gymnosperms are naked and exposed to the
environmental, whereas the seeds of flowering plants (angiosperms)
from with a protective structure called the fruit. In both cases, the egg
inside the ovule is fertilized by a male nucleus through a pollen grain.
This process is called pollination in plants. Seeds are primary sources
for a variety of foods like wheat, rice, corn, beans, peas, peanuts and
so on. Essentials like cooking oil are created from seeds of flax,
cotton, soybeans, sunflower, coconut and so on.
DICOT SEEDS
Dicotyledon, byname dicot, any member of the flowering plants, or
angiosperms that has a pair of leaves, or cotyledons, in the embryo of
the seed. There are about 175,000 known species of dicots. Most
common garden plants, shrubs and trees, broad-leafed flowering
plants such as magnolias, roses, geraniums, and hollyhocks are
dicots.
Dicots typically also have flower parts (sepals, petals, stamens, and
pistils) based on a plan of four or five, or multiples thereof, although
there are exceptions. The leaves are net-veined in most, which means
the vessels that conduct water and food show a mesh like pattern. In
the stems the vessels are usually arranged in a continuous ring near
the stem surface. About 50 percent of all dicot species are woody; they
show an annual increase in stem diameter as a result of the
production of new tissue by the cambium, a layer of cells that remain
capable of division throughout the life of these plants. Branching of
stems is common, as are taproots. The microscopic pores (stomates)
on the leaf surfaces are usually scattered and are in various
orientations. The pollen grains typically have three germinal furrows
or pores (tricolpate condition), except in the more primitive families.
Parts and Function of a Dicot seed:
Epicotyl- An epicotyl is important for the beginning stages of a plant’s
life. It is the region of a seedling stem above the stalks of the seed
leaves embryo plant. It grows rapidly, showing hypogeal germination,
and extends the stem above the soil surface.
Hypocotyl- The hypocotyl extends the radicle into the soil which will
later form the roots. In epigeal germination, the extension of the
hypocotyl pushes the cotyledons and epicotyl above the surface of the
soil.
Radicle- Radicle is capable of absorbing water from the soil, which is
required for the development of the embryonic plant. Radicle absorbs
water and nutrients and supplies to the leaves for starting
photosynthesis.
Seed coat- (Sometimes called the Testa) The seed coat function is
simultaneously to protect the embryo and to transmit information
regarding the external environment. An impenetrable seed coat may
help to keep the embryo safe, but at the same time it would exclude
the sensing of environmental cues.
Cotyledon- In dicot plants, the cotyledons are photosynthetic and
function like leaves. The cotyledons are the first part of the plant to
emerge from the soil. Some cotyledons last only days after growing
from the soil and give way for other plant growth, while some
cotyledons can last for years.
Embryo- A typically dicotyledons embryo consist of an embryo axis
and two cotyledons. The part of embryonal axis above the level of
cotyledons is called epicotyl. It terminates with the stem tip, called
plumule (future shoot).
MONOCOT SEEDS
Monocotyledon, by name monocot, one of two great groups of
flowering plants, or angiosperms, the other being the eudicotyledons
(eudicots). There are approximately 60,000 species of monocots,
including the most economically important of all plant families,
Poaceae (true grasses), and the largest of all plant families,
Orchidaceae (orchids). Other prominent monocot families include
Liliaceae (lilies), Arecaceae (palms), and Iridaceae (irises). Most of
them are distinguished by the presence of only one seed leaf, or
cotyledon, in the embryo contained in the seed. Eudicotyledons, in
contrast, ordinarily have two cotyledons.
Monocots form a monophyletic group, meaning that they share a
common evolutionary history. It is widely believed that the monocots
were derived from primitive eudicots. Given that the various physical
features of monocots are regarded as derived characteristics within
the angiosperms, any plant more primitive than the monocots in these
several respects would certainly be a eudicot. Some of the earliest
known monocot fossils are pollen grains dating to the Aptian Age of
the Early Cretaceous epoch (125 million-113 million years ago).
Molecular clock studies (which employ differences in DNA to estimate
when a group split from its ancestors) suggest that monocots may
have originated as early as 140 million years ago.
Parts and Function of a monocot seed:
Endosperm- The endosperm plays an important role in supporting
embryonic growth by supplying nutrients, protecting the embryo and
controlling embryo growth by acting as a mechanical barrier during
seed development and germination.
Cotyledon- In many monocots, the cotyledon acts as a special
absorbing organ to mobilize the reserve materials and withdraw them
from the endosperm; e.g., in grasses, the cotyledon has been modified
into an enzyme-secreting scutellum (“shield”) between embryo and
endosperm.
Seed coat- The seed coats function is simultaneously to protect the
embryo and to transmit information regarding the external
environment.
Radicle- The radicle is the embryonic root of the plant, and grows
downward in the soil. It is the first thing to emerge from a seed and
down into the ground to allow the seed to suck up water and send out
it leaves so that its starts photosynthesizing.
Hypocotyl- Monocots, such as corn (right), have one cotyledon, called
the scutellum, which channels nutrition to the growing embryo. Both
monocot and dicot embryos have plumule that forms the leaves, a
hypocotyl that forms the stem, and a radicle that forms the root.
Epicotyl- In monocots plants, the first shoot that emerges from the
ground or from the seed is the epicotyl, from which the first shoots
and leaves emerge. Lengthening of the epicotyl is thought to be
controlled by the phytochrome photoreceptors.
Embryo- The embryo of each seed plant possesses one or more leaf-
like structures called cotyledons, which absorb nutrients and may
function as the first leaves in some plants. Monocots have a single
such cotyledon, while other flowering plants usually have two.
II. OBJECTIVE
At the end of the activity the students should be able to identify
and discuss seed and its structures.
III. MATERIALS
Dicot seeds- Bean seeds (another medium to large seed could be
substituted)
Monocot seed- Corn seeds
Cotton ball
Container for soaking
Water
Softened Lima bean or large dried bean for dissection
- Bowl of water to soften the seed. You will want to let the
dried bean soaked for 12-24 hours
Magnifying glass (optional)
Iodine solution
Scalpel or sharp paper cutter
Dissecting needle or needle
IV. PROCEDURE
Dissecting the Bean:
1. Soften 12 beans by soaking in tap water for 8 hours.
Figure 1: Soaked beans and corn seeds
2. Split the softened bean in half, there is a line that runs down
the middle of the seed coat. Use that line to split the bean in
half. You may need to use the knife to cut through the bean
coat.
Figure 2: Bean seeds cut into half
3. Examine the inside of the bean. Use a magnifying glass to see
all the details of the bean. Draw what you see.
4. Stain the embryo part with iodine solution.
Figure 3: Stained been seeds
5. Dab the stained part with tissue paper to remove excess iodine.
6. Identify the part of the seed. You should see the cotyledons,
embryo and seed coat.
7. Take the picture of the bean seed and draw the seed parts.
Figure 4: Bean seed structure
Dissecting the corn seed:
1. Soften 12 corn seed by soaking in tap water 8 hours.
Figure 5: Soaked beans and corn seeds
2. Locate the apron-like structure or embryo of the seed by observing
the surface of the seed.
3. Cut the seed in half along the apron-like structure or embryo.
Figure 6: Corn seeds cut into half
4. Stain the cut surface with iodine then let it settle into the seed. Do
the procedure 1 or 3 if you commit error.
Figure 7: Stained the corn seeds
5. Identify the different parts of the corn seed.
6. Take the picture of the cut surface then draw the seed parts.
Figure 8: Corn seeds structure
V. REFERRENCES
Kruglova, N.N., Titova, G.E., Seldimirova, O.A. et al. Embryo of Flowering
Plants at the Critical Stage of Embryogenesis Relative Autonomy (by Example
of Cereal). Russ J Deev Biol 51, 1-15(2020).
https://doi.org/10.1134/S1062360420010026
Radchuk Volodymyr, Borisjuk Ljudmilla. Physical, metabolic and
Developmental functions of the seed coat. Frontiers in plant Science. VOL 5,
2024, PAGES 51o. DOI=10.3389/fpls.2014.00510
Augustyn A. 2021, August 15. Dicotyledones, Magnoliopsida, dicot.
The Editors of Encyclopaedia Brittanica.
https://www.brittanica.com/plant/dicotyledon
Petruzzelo M. 2021, January 06. Liliopsac, Monocotyledonae, monocot. The
Editors of Encyclopaedia Brittanica.
https://www.Brittanica.com/plant/monocotyledon
Stock illustrations/ corn
Stock illustrations/ bean seed structure
https://byjus.com/biology/difference-between-monocotyledon-and-
dicotyledon/
Amber A. 2021, October 1. Monocot vs. Dicot: Difference and Comparison. The
Editors of Encyclopaedia Brittanica.
https://www.brittanica.com/plant/differences
