Plant Growth and Tissues

• Plants/shoots grow upwards, while roots grow downwards.
• Plants emerge from a seed, with the first leaf/root emerging initially.
• Growth in length is termed primary growth.
• Growth in width is termed secondary growth.

Main Tissues

• Dermal tissue forms the protective layer.
• Vascular tissue includes the epidermis (outer layer), mesophyll (inner layer), xylem, and phloem.
• Vascular tissue supports plant growth in stems and branches.
• Ground tissue is composed of xylem and phloem.
• Xylem transports water from roots to the upper parts of the plant.
• Phloem transports food from photosynthesis to other areas of the plant.
• Ground tissue forms the skeleton of the plant.
• Ground tissue includes the epidermis, cortex (support), phloem, xylem, and pith (inner center).

Meristems

• Meristems are found at the tips of plants.
• Primary/apical meristems include the shoot apex, root apex, procambium, protoderm, and ground meristems.
• Primary/apical meristems facilitate length growth.
• Primary/apical meristems produce emerging leaves/flowers for certain plants.
• Secondary/lateral meristems include the vascular cambium, located between the procambium.
• Secondary/lateral meristems include the cork cambium, located between the protoderm and ground meristem.
• Secondary/lateral meristems enable width growth, demonstrating active cell growth/division.

Shoot

• Shoot contains lateral, apical, and ground meristems.

Root

• The root contains lateral, ground, and apical meristems.
• Root hairs are present.
• The root cap protects the root.
• The root cap protects roots from damage during growth in harsh soil.
• The root cap directs the roots' downward growth.
• Without a root cap, roots may grow incorrectly, i.e., sideways.

Basic Plant Morphology

• Plants consist of two systems: the shoot system and the root system.
• Plants have six organs: vegetative (root, stem, leaf) and reproductive (flower, fruit, seed).

Basic Tissue Types

• The three basic tissue types are dermal (outer), ground (center), and vascular (inner).
• In botany/zoology, structure determines function.

Simple Tissues

• Simple tissues consist of one cell type.
• Dermal tissue includes stomates/stomata and trichomes.
• Trichomes are found in roots and stems, extending from the plant.
• Trichomes efficiently capture water and/or nutrients.
• Some trichomes are visible to the naked eye and act as extra "hands" for catching nutrients.
• Trichomes can be non-glandular or glandular.
• Root hairs help in capturing water and are found only in roots.

Ground Tissue

• Parenchyma has thin walls and is alive at maturity.
• Parenchyma is multifaceted, facilitating photosynthesis, storage, secretion (glands and trichomes), mitosis, wound healing, cloning, and protection (epidermis).
• Collenchyma has unevenly thickened walls with varied thickness.
• Collenchyma is alive at maturity and mainly supports primary growth.
• Sclerenchyma has evenly thickened cell walls and is dead at maturity.
• Sclerenchyma provides strength/support/protection and includes fiber and sclereids.

Vascular Tissue

• Xylem primarily conducts water and nutrients.
• Phloem primarily conducts sugars and amino acids, i.e., food.

Complex Tissues

• Complex tissues are made up of more than one cell type.

Xylem

• Xylem is water-conducting tissue incorporating parenchyma, vessels (big holes for water entry), tracheids (small holes for efficient water transport), and ray cells.

Phloem

• Phloem facilitates food conduction and includes sieve-tube cells, companion cells, fibers, parenchyma, and ray cells.
• Sieve-tube cells lack a nucleus at maturity but have cytoplasm.

Periderm

• Periderm is a protective covering composed of cork and parenchyma.

Secretory Structures

• Secretory structures produce and store latex, resin, nectar, and other substances in channels within the plant body.

Vessel Member

• Vessel members are wider, shorter, thinner-walled, and less tapered.
• Vessel members are aligned end-to-end, forming micropipes with perforated end walls.

Tracheids

• Tracheids are long, thin cells with tapered ends.
• Tracheids have secondary walls hardened with lignin.
• Water moves between cells through pits.

Sieve-Tube Cell

• The sieve-tube cell includes a sieve-tube member.
• It also contains a companion cell with a nucleus.
• Companion cells are needed because sieve-tube members lack their own nucleus.
• It also has a sieve plate.