Exercise 5: Gymnosperms

Spermatophytes

are vascular plants that reproduce through seeds rather than spores

gymnosperms and angiosperns

They are divided into two major groups:

• _____→ “naked seeds” (not enclosed in fruits)

• _____→ flowering plants with seeds enclosed in fruits

seed

A _______ is a mature ovule containing:

• Embryo (young sporophyte)

• Stored nutrients (endosperm or female gametophyte tissue)

• Protective seed coat

microspores and megaspores

All seed plants are heterosporous, producing:

pollen grains

_______ carry the male gametophyte

pollen grains

Function:

• Deliver sperm cells to the egg

• Eliminate the need for free water in fertilization

ovule

The _________ contains:

• Megasporangium (nucellus)

• Integuments (protective layers)

• Female gametophyte

Gymnosperms

are seed plants that produce “naked seeds”, meaning seeds are not enclosed in an ovary or fruit

embryo, nutritive tissue, seed coat

Gymnosperm seeds consist of:

heterosporous

Gymnosperms are _________, producing microspores (male) and megaspores (female). Fertilization does not require water, unlike ferns or lycophytes.

microstrobili (male cones)

• Smaller, often on lower branches

• Contain microsporangia producing pollen

• Short-lived

megastrobili (female cones)

• Larger, often on upper branches

• Contain ovules

• Woody, persistent

• May take 1–3 years for seeds to mature

Conifers

Pine sporophyte generation produces: pollen cone and ovulate cone. Examples: pine, spruce, fir, cedar

Key features:

• Needle-like leaves

• Monoecious

• Secondary xylem abundant (wood)

• Seeds on cone scales

• Wind-pollinated

Cycads

Examples: Cycas, Zamia
Key features:

• Palm-like appearance

• Dioecious (separate male and female plants)

• Motile sperm (unique among gymnosperms)

• Mostly tropical

Gingko

Example: Ginkgo biloba
Key features:

• Fan-shaped leaves

• Dioecious

• Motile sperm (like cycads)

• Living fossil (only one extant species)