Divisions of Seed Plants

1
Divisions of Seed Plants
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Div GnetophytaThe Gnetophytes

• 1. Are gymnosperms.
• 2. Have vessels as well as tracheids.
• 3. Interval between pollination and fertilization
  is short.
• 4. Mostly dioecious.
• 5. Embryogengy has a more limited free nuclear
  period.
• 6. Pollen chamber extends to female gametophyte -
  short pollen tube rapid fertilization.

3
Div GnetophytaOrder Gnetales Geneus Ephedra

• 1. Resembles whisk ferns.
• 2. Most of the photosynthesis occurs in new
  branches.
• 3. Leaves appressed against stem.

• 24-3

4
Div GnetophytaOrder Gnetales Geneus Ephedra

• 1. Resembles whisk ferns.
• 2. Most of the photosynthesis occurs in new
  branches.
• 3. Leaves appressed against stem.

• 24-3

5
Div GnetophytaOrder Ephedrales Genus Ephedra
6
Div GnetophytaOrder Gnetales Geneus Ephedra

• 1. Resembles whisk ferns.
• 2. Most of the photosynthesis occurs in new
  branches.
• 3. Leaves appressed against stem.
• 4. Compound megastrobili and simple microstrobili.

• 24-6 C, D, E

7
Div GnetophytaOrder Gnetales Geneus Ephedra

• 1. Resembles whisk ferns.
• 2. Most of the photosynthesis occurs in new
  branches.
• 3. Leaves appressed against stem.
• 4. Compound megastrobili and simple
  microstrobili.

• 24-6 C, D, E

8
Div GnetophytaOrder Gnetales Geneus Ephedra

• 1. Resembles whisk ferns.
• 2. Most of the photosynthesis occurs in new
  branches.
• 3. Leaves appressed against stem.
• 4. Compound megastrobili and simple
  microstrobili.

• 24-6 C, D, E

9
Div GnetophytaOrder Gnetales Geneus Ephedra

• Young ovule

10
Div GnetophytaOrder Gnetales Geneus Ephedra

• Mature ovule
• 24-12

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Div GnetophytaOrder Welwitschiales
GenusWelwitschia

• 1. Long underground stems.
• 2. Straplike leaves - basal meristem.
• (intercalary growth)