Plant Evolution, Structure, and Reproduction

Comprehensive vocabulary terms covering plant evolution, anatomical structures, tissue systems, and reproductive cycles based on the lecture notes.

Cuticle

A waxy coating on leaves that serves as an adaptation to prevent water loss in terrestrial environments.

Stomata

Tiny pores that open and close to allow gas exchange—specifically $CO_2$ in and $O_2$ out—while minimizing water loss.

Vascular Tissue

A system of tubes consisting of xylem, which transports water from roots, and phloem, which distributes sugars from leaves.

Lignin

A chemical that hardens cell walls, providing structural support to allow plants to stand upright against gravity.

Gametangia

Protective jackets of cells that keep plant gametes and embryos moist.

Bryophytes

Non-vascular plants, such as mosses, that lack roots and require water for swimming sperm to achieve fertilization.

Seedless Vascular Plants

Plants like ferns that developed xylem and phloem to grow tall but still require water for fertilization.

Gymnosperms

Naked seed plants, such as conifers, that developed pollen and seeds to reproduce completely away from water.

Angiosperms

Flowering plants that developed flowers to attract pollinators and fruits for seed dispersal.

Gametophyte generation

The haploid ($n$) multicellular stage in the plant life cycle that produces gametes via mitosis.

Sporophyte generation

The diploid ($2n$) multicellular stage in the plant life cycle that produces spores via meiosis.

Mycorrhizae

Mutualistic relationships where fungi absorb phosphorus and minerals for plant roots while receiving photosynthetic sugars in return.

Root hairs

Small extensions of the root system that vastly increase the surface area for the absorption of water and minerals.

Stolon

Also known as "runners," these are modified stems that grow horizontally along the ground to allow for asexual reproduction.

Rhizomes

Horizontal underground stems, such as those found in ginger, used for growth and storage.

Tubers

The swollen ends of rhizomes, such as potatoes, specialized for carbohydrate storage.

Dermal Tissue System

The outer protective covering of a plant, containing the cuticle, stomata, and guard cells.

Vascular Tissue System

A tissue system made of xylem and phloem that provides structural support and facilitates long-distance transport.

Ground Tissue System

Plant tissue that fills the space between dermal and vascular systems, responsible for photosynthesis, storage, and support.

Parenchyma Cells

The most abundant plant cells, which are alive at maturity, have thin walls, and perform photosynthesis and food storage.

Collenchyma Cells

Cells that provide flexible support to actively growing plant parts using unevenly thickened primary cell walls.

Sclerenchyma Cells

Cells with thick secondary walls hardened with lignin that provide rigid support; they are typically dead at maturity.

Sieve-Tube Elements

Food-conducting cells of the phloem that are alive at maturity but lack a nucleus and organelles to facilitate sugar flow.

Meristems

Tissues containing unspecialized cells that perpetually divide to generate new cells for plant growth.

Apical Meristems

Meristems located at the tips of roots and buds of shoots that drive primary growth to elongate the plant body.

Secondary Growth

Growth that increases the diameter of woody plants, driven by lateral meristems.

Vascular Cambium

A cylinder of meristematic cells that produces secondary xylem (inner wood) and secondary phloem (outer bark).

Double Fertilization

A process where one sperm fertilizes the egg to form a diploid ($2n$) zygote and another fuses with two haploid nuclei to form a triploid ($3n$) cell.

Endosperm

A nutrient-rich triploid ($3n$) tissue that develops from double fertilization to feed the plant embryo inside the seed.

Dormancy

A state of metabolic shutdown where a seed loses water and survives harsh conditions until environmentals factors are favorable for sprouting.

Imbibition

The process of a seed absorbing water, which triggers expansion, the rupture of the seed coat, and the start of germination.