21 Gymnosperms

These flashcards cover key concepts about gymnosperms from their evolutionary significance, structures, adaptations, and classifications.

What major evolutionary innovation is responsible for the dominance of seed plants among today’s flora?

The evolution of the seed.

What is the function of seeds in terms of plant survival?

Seeds protect from desiccation and provide stored food for development.

What are the two types of spores produced in gymnosperms?

Megaspores (female) and microspores (male).

What does the formation of an ovule develop into?

A seed containing an embryo.

What is an integument in the context of seeds?

The layers of tissue surrounding the megasporangium.

What led to the development of the ovule in gymnosperms?

The megasporangium retained its structure and did not release spores.

What is a characteristic of progymnosperms?

They represent a transition between seedless vascular plants and seed plants.

Name two extinct groups of gymnosperms.

Pteridospermales (seed ferns) and Cordaitales (primitive and conifer-like).

How are living gymnosperms characterized?

They have 'naked seeds' not protected by an ovary or fruit.

What are the four phyla of living gymnosperms?

Coniferophyta, Cycadophyta, Ginkgophyta, Gnetophyta.

What is the primary mode of dispersal for pollen grains in gymnosperms?

Dispersal is generally via wind.

What is polyembryony in gymnosperms?

The occurrence when megagametophytes produce several archegonia with more than one egg being fertilized.

What makes Phylum Coniferophyta ecologically important?

It contains the most numerous and widespread members of gymnosperms, including economically valuable plants.

What adaptations do Pinus leaves have for dry environments?

A thick cuticle, sunken stomata, and hypodermis of thick-walled cells.

What kind of growth begins early in Pinus stems?

Secondary growth that leads to a large amount of secondary xylem.

What is the reproductive cycle duration of other conifers compared to Pinus?

3 days to 4 weeks, compared to 15 months in pines.

What is a unique feature of Taxus?

It has a fleshy ovulate structure called an aril that attracts birds for seed dispersal.