Seeds
…baby plants waiting to
emerge
What are seeds?
• seeds are plant embryos with
stored foods
• seeds are formed when plant
pollen (sperm) fertilizes the egg,
found in the ovule of the plant
Seeds
• The biological function of seeds
is for the propagation of the
species
Seeds are found inside the fruit of the plant.
Seed vocabulary
• germination –
when the plant
embryo/seed
starts to grow
• seed dormancy
– a period of time
before the seed
will germinate
• seed dispersal –
how seeds get
around
• viability – time
period in which
seeds can be
expected to
germinate
Testa a.k.a. Seed Coat
• the seed coat is the protective covering
of the seed
• scarification “scars” the seed coat so
the germination of the seed is
encouraged
• scarification methods include creating
cracks or nicks, freezing/thawing, or
dipping the seed in acid
Cotyledons
• cotyledons are the first small leaves of
the plant, A.K.A. “seed leaves”
• the cotyledons absorb or store food
• provide energy before the plant
emerges from under the soil
• cotyledons can hold the endosperm, the
food storage tissue of the seed
Epicotyl
• the small leafy structure inside the
seed
Hypocotyl
• the thicker section of the embryo
Radicle
• the lower end of the hypocotyl that
becomes the plant’s primary root
Amazing seeds…
• To function in propagation, seeds
must be alive
• Seeds respire, though slowly
– consume O2, produce CO2 and H2O
• Seeds have a finite lifespan
– they cannot be stored indefinitely
How does a seed
grow up to be a plant?
• Germination, which requires
– Water - for imbibition (taking up of
fluid, resulting in swelling)
– Oxygen - for cellular respiration
– Suitable temperature
Seeds grow into plants…
• Outcome of successful germination
is a seedling capable of
independent growth
• that independent growth continues
with photosynthesis because the
energy found in the cotyledon has
been used up