Gymnosperms

Outline

Gymnosperms

• Coniferophyta (550 spp)
• Cycadophyta (140 spp)
• Ginkgophyta (1 sp.)
• Gnetophyta (3 genera, 70 spp) [may have close common ancestry with the Anthophyta]

Coniferophyta

Introduction

• bear cones
• 2° growth by means of cambium
• needle- or scale-like leaves
• resin canals

Life cycle

[see class notes and text]

Ecological and economic importance

Ecological

trees... dominant in taiga & cypress swamps

as dominant plants they provide structure, habitat, food, etc.

Economic

wood

• fuel
• lumber
• pulpwood

seeds

• pine nuts

resin (= pitch)

pitch -- sealing boats, casks

volatile components of pitch -- turpentine

nonvolatile components -- rosin

fossil resin -- amber

other -- juniper berries (gin), fake lemonade, retsina

Cycadophyta

Introduction

• a.k.a. cycads
• palm-like
• have 2° growth
• many have anti-herbivore toxins
• some are symbiotic with Nostoc

Reproduction

like pines, but:

• dioecious
• pollen produces flagellated sperm
• egg cells large
• insect pollination

Economic uses

ornamental plants

Ginkgophyta

Introduction

• 1 species = Ginkgo biloba = maidenhair tree
• odd leaf morphology
• 2° growth and true wood

Reproduction

like pines, but:

• dioecious
• pollen produces flagellated sperm
• seeds have a fleshy seed coat = aril
• females are stinky

Economic uses

• urban trees
• edible seeds
• apparent medicinal applications

Gnetophyta

Introduction

• 3 genera, 3 orders
• weird plants
• have cones
• some insect pollination
• fancy vascular tissue: vessel elements
• 2° growth
• double fertilization

Gnetum

• SE Asia, Africa, Amazonia
• tropical vines and shrubs

Ephedra

• SW U.S., N Mexico
• "joint firs," "Mormon tea"
• source of drug ephedrine

Welwitschia mirabilis

• S African deserts
• bizarre morphology

Vocabulary

click here to go to gymnosperm vocabulary