SeedsSeeds

What are seeds?What are seeds?

Parts of a seed – seed coatParts of a seed – seed coat

• Why do seeds have a seed coat?

Why do seeds have a seed coat?

Why are seeds so different?Shape Size Colour Texture

• Cactus seed under a powerful microscope

Seed coat textureSeed coat texture

Parts of a seedParts of a seedThe seeds for new life are found inside fruit. They contain everything necessary for the growth and development of a new plant. The three primary parts of a seed are the embryo, endosperm, and seed coat. The embryo is the young multicellular organism before it emerges from the seed. The endosperm is a source of stored food, consisting primarily of starches. The seed coat consists of one or more protective layers that encase the seed.

Parts of a seedParts of a seedThe seed is encased in a protective seed coat. It protects the embryo and the endosperm from drying and from physical injury. A scar can be seen at the end or along the side of the seed coat. It is called the hilum. The hilum marks the point of attachment of the seed to the ovary wall. The seed coat has a tiny opening, sometimesvisible near the hilum, called themicropyle.

Parts of a seed – Inside the seedParts of a seed – Inside the seed

The mature embryo consists of an embryonic root known as the radicle, an embryonicshoot, and one or two cotyledons. The embryonic shoot, known as the plumule, has twomain parts, the epicotyl and the hypocotyl.

Parts of a seed – Inside the seedParts of a seed – Inside the seedThe epicotyl is the portion of the embryonic stemabove the point at which the stem is attached to the cotyledon(s). The hypocotyl is the portionbelow the point of attachment. The hypocotyl is connected to the radicle. The cotyledonis described as a seed leaf that stores food in the

form of starch and protein for use by theembryo.

Parts of a seed – Inside the seedParts of a seed – Inside the seed

An embryo of a monocotyledon (monocot) plant has one cotyledon, while that of a dicotyledon (dicot) plant has two cotyledons. A monocot stores the bulk of its energy in the endosperm. A dicot stores its food in the two cotyledons.

Parts of a bean seedParts of a bean seed

First leaves

Epicotyle = stem

Parts of a corn seedParts of a corn seed

Monocot vs Dicot seedMonocot vs Dicot seed

Monocot vs Dicot seedMonocot vs Dicot seed

What do seeds need to What do seeds need to GERMINATE?GERMINATE?

Oxygen - Growth

TemperatureTemperature – Cold? Hot? Warm?

WaterWater - Photosynthesis and growth

GERMINATIONGERMINATIONWhat is germination?

Steps:1. Seed coat breaks

2. Radicle becomes ROOT

3. Hypocotyl and epicotyl become the STEM

4. First leaves grow = PHOTOSYNTHESIS

First leaves

Plants need NUTRIENTSPlants need NUTRIENTS

CarbonCarbon

OxygenOxygen

HydrogenHydrogen

Soil nutrientsSoil nutrients

Nitrogen – Growth, photosynthesis

Phosphorus – photosynthesis, flowering

Potassium – build proteins, prevent disease

Calcium – Strong cells

Magnesium – Photosynthesis

Sulfur - build proteins and produce food

Soil nutrientsSoil nutrients

Soil quality - pHSoil quality - pH

pH=7