Gymnosperms

Divisions

• Pinophyta (Conifers)

• Gnetophyta

• Ginkophyta

• Cycadophyta

Conifers

• most species = single straight trunk with side branches

  • evergreens

Fascicles

needles in bundles

Male Cones

• strobilus

• pollen cone

  • microsporangiate cone

Female Cone

• strobilus

• ovulate cone

  • megasporangiate cone

Pollen Cones

• single short unbranched axis with leaf-like microsporophyll

• each microsporophyll bears two microsporangia → contain microsporocytes → 4 microspores → pollen grain

Pollen Grain

immature microgametophyte

• Contains 4 cells when released

  • tube cells

  • generative cells

  • prothallial cells

Ovulate Cones

• house multiple megasporangia arranged on megasporophylls

• compound - Ovuliferous scale + sterile bract beneath

Conifer Seeds

embryo (2n) enclosed in megagametophyte (n) surrounded by nucellus (2n) and seed coat (2n)

White Spruce First Nation Use

Roots → baskets, cords, ropes

Firewood → heating, cooking, smoking

Young Cones → boiled → treat toothaches

Western Red Cedar Uses

Textiles - hats, capes

Healing - treat upper respiratory aliments, wounds (antimicrobial)

Ceremonial - totem poles, masks

Construction - dugout canoes, house posts

Cycadophyte - Cycads

“palm-like+ gymnosperms

• tropical

• distinct trunk

• large evergreen leaves

• dioecious

• motile sperm

Dioecious

male and female cones are on different plants

• microstrobilus cones (pollen)

• megastrobilus cones (ovulate)

Ginkophyta - Ginkgo

• distinct fan shaped leaves with dichotomous venation

• deciduous

• dioecious

• pollination drop draws pollen into ovule

Deciduous

sheds leaves annually

Ginkgo Pollen Tubes

• highly branched

• resemble haustoria

• might acquire nutrients from nucellus

Gnetophyta - Ephedra

• one genus with species found in arid regions (deserts)

• shrubs with photosynthetic stems and reduced scale-like leaves

• sperm not flagellated, not mobile

Gnetophyta - Gnetum

• one genus distributed in tropics

• trees and climbing vines with leathery leaves

• megasporangiate structures develop into fleshy seeds

• microsporangiate structures look more floral less cone

Gnetophyta - Welwitschia

• produces only two leaves in lifetime

• in Namibia

• pollen and ovulate cones arise from the disc in center of plant

Gnetophyta Share Angiosperm Characteristics

• more closely related to conifers

• vessels

• double fertilization (Ephadra)

• Gnetum and Welwitschia lack archegonia

• some cones resemble flowers

• some species produce nectar

• many species rely on insect pollen