Dicots versus Monocots

• Dicots • Monocots

• Two cotyledons • One cotyledon • parts in fours or • Flower parts in threes fives • Leaves with parallel • Leaves with distinct primary veins. vein network • Vascular cambium • Vascular cambium present absent

• Vascular bundles in • Vascular bundles ring scattered

• Pollen grain with three • Pollen grain with one apertures aperture Fruit and Dispersal

• Water Dispersal

! Some fruits contain trapped air.

! Some have a waxy coating.

! Both means help the seed to float.

! Example- coconut

• Mechanical Ejection of

! Capsules dry and split in a way that flings the seeds far from the parent plant.

! Example witch hazel

Fruit and Seed Dispersal

• Wind Dispersal

! Small and Lightweight seeds.

! May have attachments like wings or hairs to help give them lift.

! Example- maple, ash, dandelion

• Animal Dispersal

! Seeds can pass through an animal’s digestive tract.

! Some fruits and seeds have spines or thorns that catch in fur or feathers.

! Oils attract ants. Corn- pollinated by wind Birds, Butterflies, and Bats How Seeds Form

• Pollination is the transfer of pollen from an anther to a stigma.

• This may occur by wind or pollinating insects, birds or other animals.

• Wind pollinated usually lack showy floral parts and nectar since they don’t need to attract a pollinator.

• Their non-showy flowers, however, do produce a lot of pollen to increase the likelihood that a pollen grain will land on a receptive stigma. How Seeds Form

• Brightly colored flowers, those with distinct markings or patterns on petals, containing fragrance or nectar, are most likely pollinated by insects, birds, or other animals. How Seeds Form

• The surface of the stigma contains a chemical which activates the pollen, causing it to grow a long tube down the inside of the style to the ovules inside the ovary.

• Fertilization is the union of the male sperm nucleus from the pollen grain and the female egg found in the ovary.

• If fertilization is successful, the ovule will develop into a seed. How Seeds Form

• Self-pollinating plants are capable of fertilizing themselves. That is, pollen from a single plant unites with an egg on the same plant.

• In some plants, self-pollination may take place before the flower even opens.

• In others, complex floral structure decrease the probability that pollen from another plant will reach the ovule. How Seeds Form

• Cross-pollination occurs when pollen from one plant fertilized the ovule of a genetically different plant.

• The surface of the stigma of self- incompatible plants recognized its own pollen and prevents it from , or causes the pollen to grow so slowly that it is not likely to reach the ovule before another pollen grain fertilized the ovule. How Seeds Form

• Many fruit trees require cross-pollination for fruit development. How Seeds Form

• Structure

! Cotyledons - Food storage organs that function as first seed leaves.

! Plumule - Embryo shoot.

! Epicotyl - Stem above cotyledon.

! - Stem below attachment point.

! Radicle - Stem tip developing into a root.