USABO PLANTS

Parenchyma

Living, metabolically active cells that make up the bulk of non-vascular plant tissues. Living at maturity, Thin primary cell walls, No secondary wall, Large central vacuole, Often retain the ability to divide (totipotent)

Collenchyma

Living support cells that provide flexible mechanical support in growing regions. Living at maturity, Unevenly thickened primary cell walls, Wall thickening rich in: Cellulose, Hemicellulose, Pectin, No lignin, Elongated shape

Sclerenchyma

Rigid support cells with thick, lignified secondary walls. Usually dead at maturity, Very thick secondary cell walls, High lignin content, Extremely strong, No metabolic activity at maturity

Sclerenchyma Fibers

Structure: Long, Narrow, Tapered ends, Thick secondary walls

Functions: Tensile strength and load bearing

Found around vascular bundles

Sclerenchyma Sclereids

Structure: Shorter, Irregular or isodiametric, Extremely thick walls

Functions: protection and hardening of tissues

Found in seed coats, nutshells

Bryophytes

Nonvascular; Examples: mosses, liverworts, hornworts. No xylem or phloem. No true roots, stems, leaves. Gametophyte-dominant. Need water for fertilization. Small, low-growing

Tracheophytes

Vascular Plants

Seedless Vascular Plants

Examples: ferns, horsetails; Vascular tissue present. Reproduce via spores. Need water for fertilization

Spermatophytes

Seed Plants; Pollen replaces water for fertilization

Gymnosperms

Naked Seeds; Examples: pines, firs, cycads, ginkgo. Seeds not enclosed in fruit. No flowers. Reproductive structures = cones. Mostly wind-pollinated. Xylem mostly tracheids only

Angiosperms

Covered seeds; Examples: flowering plants. Seeds enclosed in fruit. Flowers present. Double fertilization. Xylem has vessel elements. Most diverse plant group.

Monocots

Type of angiosperm. Examples: grasses, lilies, palms. 1 cotyledon. Parallel leaf veins. Vascular bundles scattered. Fibrous root system. Flower parts in 3s. Pollen with 1 aperture.

Eudicots

Type of angiosperm. Examples: beans, roses, trees. 2 cotyledons. Net-like leaf veins. Vascular bundles in a ring. Taproot system. Flower parts in 4s or 5s. Pollen with 3 apertures

Protoderm

Makes epidermis

Ground Meristem

Makes Cortex, pith (parenchyma, collenchyma, sclerenchyma)

Procambium

Makes primary xylem and phloem

Lateral Meristems

Found in dicots and gymnosperms

secondary xylem

what makes up wood

Cork Cambium

Phellogen; A lateral meristem that produces the periderm, replacing the epidermis.

Cork

Phellem. Suberin-rich, waterproof, grows outward

Phelloderm

inward, living parenchyma between secondary phloem and periderm

Periderm

Cork cambium + cork + phelloderm

Intercalary Meristems

Meristems located between mature tissues, usually at the base of leaves or internodes. Found in grasses. Rapid regrowth after grazing.

Dermal Tissue

The outer tissue system of plants responsible for protection, water retention, gas exchange, and environmental interaction.

Epidermis

A single layer of living cells forming the outermost covering of leaves, young stems, and roots.

Pavement Cells

Flattened epidermal cells that form the bulk of the epidermis and provide protection.

Cutin

A polyester of fatty acids that forms the structural matrix of the cuticle.

Epicuticular wax

Waxy substances embedded in or coating the cuticle that enhance water repellency.

Trichome

A hair-like outgrowth of the epidermis involved in protection, secretion, or reduction of transpiration.

Non-glandular Trichome

A trichome that provides physical protection, reflects light, or reduces water loss.

Glandular Trichome

A trichome that secretes substances such as oils, resins, toxins, or secondary metabolites.

Subsidiary Cells

Epidermal cells adjacent to guard cells that assist in stomatal function (common in monocots)

Dicot Stomata

Stomata with kidney-shaped guard cells, usually located on the lower leaf surface in an irregular pattern

Monocot Stomata

Stomata with dumbbell-shaped guard cells arranged in parallel rows on both leaf surfaces.