Plant Structures & Reproduction: Roots, Stems, Seeds, and Gymnosperms vs. Angiosperms

Taproot system

Taproots anchor deeply, access water/nutrients from deep soil, and store food.

Fibrous root system

Fibrous roots spread widely, prevent soil erosion, and absorb surface water/nutrients efficiently.

Adventitious roots

Roots that arise from stems or leaves, not the primary root.

Pneumatophores

Specialized roots that grow upward for gas exchange in swampy, oxygen-poor soils.

Buttress roots

Roots that stabilize tall trees in shallow, nutrient-poor soil.

Potato

A specialized stem (tuber).

Onion

A specialized stem (bulb).

Beet

A specialized root.

Node

The point where leaves or branches attach to a stem.

Internode

The stem segment between nodes.

Axillary bud

Grows into branches/flowers.

Apical bud

Located at the tip, responsible for elongation.

Rhizome

An underground horizontal stem.

Stolons

Aboveground horizontal stems that form new plants.

Tubers

Enlarged storage stems (e.g., potato).

Spines in cacti

Modified leaves; photosynthesis occurs in the stem.

Indeterminate growth

Growth that continues throughout a plant's life.

Determinate growth

Growth that stops after reaching a certain size.

Primary growth

Growth that increases length.

Secondary growth

Growth that increases thickness.

Apical meristems

Drive primary growth (lengthening).

Lateral meristems

Drive secondary growth (thickening).

Vascular cambium

Lateral meristem that produces secondary xylem and phloem.

Cork cambium

Lateral meristem that produces outer protective bark.

Primary xylem and phloem

First vascular tissues from apical meristem.

Secondary xylem and phloem

Vascular tissues from vascular cambium; xylem = wood.

Bark

All tissues external to vascular cambium (secondary phloem + periderm).

Wood

Secondary xylem.

Heartwood

Dead, inner support.

Sapwood

Active, outer water transport.

Seed components

Embryo, food supply, seed coat.

Seed coat

Diploid as it develops from the parent's sporophyte tissue.

Seed vs. spore

Seeds are multicellular, have food supply, and protective coat; spores are single cells.

Advantages of seeds

Protection, nourishment, dormancy, long-distance dispersal.

Major groups of seed plants

Gymnosperms and angiosperms.

Homosporous

Producing one type of spore.

Heterosporous

Producing two types of spores: microspores and megaspores.

Bryophytes & seedless vascular plants

Most are homosporous.

Seed plants

Most are heterosporous.

Megasporangia

Produce megaspores.

Megaspores

Give rise to female gametophytes.

Female gametophyte location

Inside the ovule.

Microsporangia

Produce microspores (pollen).

Microspores

Give rise to male gametophytes (pollen grains).

Male gametophyte location in seed plants

Inside pollen grains.

Cell division creating megaspores and microspores

Meiosis.

Megaspores and microspores

Haploid.

Megasporangia and microsporangia

Diploid.

Sperm travel to egg in seed plants

Via pollen tube; in bryophytes/seedless vascular plants, sperm swims through water.

Difference of sperm in seed plants vs bryophytes

Seed plant sperm don't need water; transported by pollen tube.

Pollen grain role in land reproduction

Protects gametophyte and delivers sperm without water.

Gymnosperms

Major group with naked seeds on sporophylls.

Sporophylls in most gymnosperms

Form cones.

Conifer

A cone-bearing gymnosperm (e.g., pine, fir, spruce).

Pine tree

A sporophyte.

Pine trees structure type

Most have both male & female structures (monoecious).

Male cone type

Pollen cone.

Cone containing microsporangia

Pollen cone.

Female cone type

Ovulate cone.

Cone containing megasporangia

Ovulate cone.

Larger cone type

Ovulate cone.

Fertilized ovule

Becomes a seed.

Earliest gymnosperm fossils age

~305 million years ago.

Earth's climate when gymnosperms became dominant

Dry and cold; gymnosperms adapted better than seedless plants.

Cycad & ginkgo sperm

Unusual because they are flagellated and motile.

Only cycad native to Florida

Coontie (Zamia integrifolia).

Cycads pollination

By insects.

Extant species in Phylum Ginkgophyta

One (Ginkgo biloba).

Plant producing ephedrine

Ephedra.

Juniper 'berries'

Actually cones.

Bristlecone pine

Some are the oldest living organisms (>4,800 years).

Welwitschia

Grows only 2 leaves for its entire life (can live >1,000 years).

Angiosperms

Major group with seeds in fruits.

Angiosperms flower production

Produce flowers.

Angiosperms appearance age

~140 million years ago.

Flower definition

A sporophyte.

Types of sporophylls in flowers

Sepals (sterile), petals (sterile), stamens (male), carpels (female).

Mature ovary

Called a fruit.

Tomato classification

A fruit because it develops from the ovary and contains seeds.

Fruits facilitate seed dispersal

By wind, water, animals (eaten, carried, stuck to fur).

Angiosperm pollen grains vs gymnosperm pollen

Angiosperm pollen has 2 sperm cells (for double fertilization).

Fertilization difference in angiosperms vs gymnosperms

Angiosperms have double fertilization (zygote + endosperm).

Food supply difference in angiosperm vs gymnosperm seeds

Angiosperms = triploid endosperm; Gymnosperms = haploid gametophyte tissue.

Cotyledon

Seed leaf; stores or transfers nutrients to embryo.

Anatomical differences between monocots & eudicots

Monocots: 1 cotyledon, parallel veins, scattered vascular bundles, fibrous roots, floral parts in 3s. Eudicots: 2 cotyledons, netlike veins, ringed vascular bundles, taproot, floral parts in 4s/5s.