Evolution of Seed Plants and Plant Body

Flashcards covering key vocabulary and definitions related to the evolution of seed plants, gymnosperms, angiosperms, flower structures, and plant body organization.

Gymnosperms

Seed plants that do not form flowers; ovules and seeds are not protected by ovary or fruit tissue.

Angiosperms

Flowering plants; ovules and seeds are enclosed in a carpel. Produce flowers and fruits.

Heterospory

Production of two different types of spores (megaspores and microspores), leading to female and male gametophytes.

Megaspores

Spores of seed plants that develop into female gametophytes (megagametophytes) within megasporangia.

Microspores

Spores of seed plants that develop into male gametophytes (microgametophytes) within microsporangia.

Megagametophyte

Female gametophyte that produces an egg; depends on sporophyte for food and water.

Microgametophyte

Male gametophyte contained within a pollen grain; depends on sporophyte for food and water.

Pollen grain

Structure containing the microgametophyte, protected by a tough coat; facilitates pollination.

Pollination

Arrival of a pollen grain near a female gametophyte.

Ovule

Megasporangium surrounded by integument, layers of sporophyte tissue; develops into a seed.

Seed

Complex, well-protected resting stage of a plant embryo; protects from drying and predators.

Wood

Proliferated xylem tissue in ancient seed plants; provides support and allows plants to grow tall.

Conifers

Gymnosperms with reproductive structures in male and female cones; seeds are protected by woody scales in female cones (megastrobilus).

Microstrobilus

Smaller male (pollen-bearing) cone

Megastrobilus

Female (seed-bearing) cone = megastrobilus. Seeds are protected by a tight cluster of woody scales—modification of branches.

Double fertilization

Unique feature of angiosperms; one male gamete fertilizes the egg, and the other fuses with two haploid cells to form triploid endosperm.

Endosperm

Nutritive tissue in angiosperm seeds that nourishes the developing embryonic sporophyte; triploid (3n) tissue.

Carpel

Modified leaf in angiosperms that encloses ovules and seeds; interacts with pollen to prevent self-pollination.

Flower

Reproductive structure of angiosperms; contains stamens and/or carpels.

Fruit

Mature ovary in angiosperms; protects seeds and promotes seed dispersal.

Stamen

Male sex structure in flowers; consists of a filament and anther.

Filament

Stalk supporting the anther in a stamen.

Anther

Pollen-producing microsporangia in a stamen.

Pistil

Female sex structure in flowers; consists of stigma, style, and ovary.

Stigma

Sticky tip of the pistil that receives pollen.

Style

Stalk connecting the stigma to the ovary in a pistil.

Ovary

Contains ovules; matures into a fruit.

Petal

Specialized sterile modified leaves (corolla) that attract pollinators.

Sepal

Specialized sterile modified leaves (calyx) that protect the flower bud before it opens.

Monoecious

Female and male flowers on the same plant.

Dioecious

Female and male flowers on different plants.

Simple fruit

Develop from single carpel (one ovary) e.g. plum, cherry.

Aggregate fruit

Develop from several carpels (ovaries). e.g. raspberry.

Multiple fruit

Develop from several flowers with each ovary come together into a larger fruit. e.g. pineapple.

Accessory fruit

Develop from parts other than carpels, not from ovary. e.g. strawberry, apple, pear

Monocots

Angiosperms with one cotyledon (seed leaf).

Eudicots

Angiosperms with two cotyledons (seed leaves).

Primary plant body

Consists of all non-woody parts of the plant and results from primary plant growth (elongation of shoots and roots).

Secondary plant body

Consists of woody tissue and bark; results from secondary plant growth (growth in diameter/width).

Vascular cambium

Produces wood and bark.

Cork cambium

Part of the bark.

Synapomorphies in the angiosperms:

Double fertilization

Endosperm – a nutritive tissue Ovules and seeds enclosed in a carpel

Flowers

Fruits

Phloem with companion cells Reduced gametophytes

Double fertilization

Microgameotphyte with

two male gametes  One male gamete + egg

other haploid (n) cells of the female gametophyte

 a triploid (3n) nucleus  a triploid tissue called