HORT90008 - Module 6: Plant Anatomy and Growth

Flashcards covering plant anatomy, meristems, primary and secondary growth, and the structural differences between monocots and eudicots.

Meristems

Embryonic tissue regions or populations of cells that retain the potential to divide.

Anticlinal division

Cell division where the plane is perpendicular to the surface of the organ; allows for elongation.

Periclinal division

Cell division where the plane is parallel to the surface of the organ; allows for outward expansion or thickening.

Radial anticlinal division

Division that is perpendicular to the surface and parallel to the axis.

Transverse anticlinal division

Division that is perpendicular to both the surface and the axis.

Procambium

A primary meristem that develops into the vascular tissue (xylem and phloem).

Ground meristem

A primary meristem that develops into the cortex, consisting primarily of parenchyma cells.

Region of cell division

The area of a growing root containing the apical meristem.

Region of elongation

The root region where cell lengthening results in most of the root's increase in length.

Region of maturation

The area where most root cells differentiate, root hairs are present, and lateral roots arise.

Amyloplasts

Organelles in the columella cells of the root cap that slide in response to gravity to help direct root growth downwards.

Apical dominance

The phenomenon where auxin produced by the apical meristem suppresses the growth of axillary or lateral buds.

Auxin

A plant hormone produced by the apical meristem that regulates apical dominance and suppresses lateral growth.

Mucigel

A substance that surrounds the root tip to lubricate its movement through the soil.

Root hairs

Extensions of epidermal cells that increase the absorptive surface area of the root.

Endodermis

The innermost layer of the root cortex, characterized by compactly arranged cells and the presence of the Casparian strip.

Casparian strip

A hydrophobic layer resulting from suberin in cell walls that forces water to transition from the apoplastic pathway to the symplastic pathway.

Apoplastic pathway

The route of water and solute movement through cell walls.

Symplastic pathway

The route of water and solute movement through the cell protoplasm.

Pericycle

The tissue layer from which lateral roots arise, categorized as endogenous (originating within).

Adventitious roots

Roots produced from above-ground structures, also known as aerial roots (e.g., prop roots).

Netted (reticulate) venation

The leaf vein arrangement characteristic of Eudicots.

Parallel venation

The leaf vein arrangement characteristic of Monocots.

Eudicots (Characteristics)

Plants typically having flower parts in fours or fives, triaperturate pollen, two cotyledons, netlike venation, and vascular bundles arranged in a ring.

Monocots (Characteristics)

Plants typically having flower parts in threes, monoaperturate pollen, one cotyledon, parallel venation, and a complex arrangement of vascular bundles.

Secondary growth

Growth that increases the diameter of roots and stems, driven by lateral meristems (vascular cambium and cork cambium).

Vascular cambium

A secondary meristem that produces secondary xylem (wood) to the inside and secondary phloem to the outside.

Cork cambium

A lateral meristem that produces the periderm (bark) to replace the epidermis.

Hardwoods

Angiosperm wood containing xylem vessels, tracheids, fibres, and parenchyma cells.

Softwoods

Conifer wood that lacks xylem vessels and fibres, instead containing tracheids and resin ducts.

Fusiform initials

Elongated meristematic cells in the vascular cambium responsible for producing secondary xylem and phloem.

Ray initials

Squarish meristematic cells in the vascular cambium that produce parenchyma cells forming wood rays.

Bark

All tissues located outside the vascular cambium.

Periderm

The secondary tissue system composed of cork, cork cambium, and phelloderm.