Plant Tissue Systems

• Three primary meristems include apical, lateral, and intercalary meristems.
• Apical meristem is at the tips of roots and shoots for primary growth, leading to stem and root lengthening.
• Lateral meristem includes vascular cambium and cork cambium for secondary growth, increasing plant girth.
• Intercalary meristem, found in grasses and monocots, allows growth at internodes, enabling growth after being cut back.
• The three primary tissues are dermal, vascular, and ground tissue systems.
• Dermal tissue system is the outer protective layer, including epidermis and cuticle.
• Vascular tissue system includes xylem and phloem, transporting water, nutrients, and food.
• Ground tissue system makes up the bulk of the plant for photosynthesis, storage, and support, and includes parenchyma, collenchyma, and sclerenchyma.

Ground Tissue System

• Parenchyma is the most common ground tissue; cells are thin-walled and flexible, involved in storage, photosynthesis, and secretion.
• Collenchyma cells have unevenly thickened walls, providing support in growing regions like petioles and stems.
• Sclerenchyma cells have thickened, lignified walls, providing structural support, and includes fibers and sclereids.
• Fibers are long, slender sclerenchyma cells.
• Sclereids are short, irregular sclerenchyma cells.

Vascular Tissue System

• Xylem transports water and minerals from the roots.
• Vessels are large, tube-like structures facilitating water transport in xylem.
• Tracheids are long, tapered cells with thick walls that aid in water conduction and support in xylem.
• Phloem transports sugars and other metabolic products.
• Sieve tube elements are tubular cells connected end to end, forming sieve tubes for nutrient transport.
• Companion cells assist sieve tube elements by providing metabolic support.
• Sieve cells are similar to sieve tube elements but mainly found in gymnosperms.
• Albuminous cells are found in gymnosperms and are associated with sieve cells.
• Xylem transports water and minerals, with lignified cells like vessels and tracheids for structural support.
• Phloem transports sugars and nutrients, characterized by sieve tubes and companion cells for nutrient movement.
• Protoxylem is the first xylem to form, positioned closer to the center and allows for stretching as the plant grows.
• Metaxylem is the later-formed xylem, developing after initial growth, more mature and less stretchy.
• Xylem function is water and nutrient transport.
• Phloem function is transport of food, especially sugars and other metabolites.
• Callose is a carbohydrate that forms at sieve plates when phloem is damaged, sealing off the area to prevent sap loss.
• Fibers are long, lignified cells providing structural support and rigidity, examples including flax and hemp.
• Simple tissues are composed of a single cell type such as parenchyma, collenchyma, and sclerenchyma.
• Compound tissues are made up of multiple cell types, such as xylem and phloem.
• Stomata structure includes two guard cells and a pore.
• Stomata function allows gas exchange and water vapor loss.
• Stomata are mainly found on the underside of leaves.
• Fibrous roots are a dense, branched network growing from the stem base, common in monocots.
• Taproots are a main, thick root growing downward with smaller lateral roots, common in dicots.
• Root functions include anchorage, water and nutrient absorption, and food storage.
• Rhizosphere is the region around the roots, rich in microorganisms, playing a role in nutrient cycling and mutualistic relationships.
• Root apical meristem is at the root tip, responsible for primary growth.
• Root apical meristem cells include protoderm (epidermis), ground meristem (ground tissue), and procambium (vascular tissue).
• Regions of a growing root include the root cap, cell division region, elongation region, and maturation region.
• Maturation region is where cells differentiate into specific tissue types.
• Root tissues in cross-section: epidermis, cortex, endodermis, and vascular cylinder. Water pathway enters through the epidermis, passes through the cortex, and reaches the xylem.
• Casparian strip is a band of suberin in the endodermis blocking passive flow, forcing passage through cell membranes for selective uptake.
• Root secondary growth occurs in dicots allowing the vascular cambium and cork cambium to produce new vascular tissue and bark.
• Endodermis is the innermost layer of cortex, regulating water and nutrient flow into the vascular cylinder.
• Exodermis is the outermost layer of the root, providing protection against water loss and pathogens.
• Pits in vascular tissue allow water and solute movement between xylem cells, tracheids, and vessels.
• Eudicot root cross-sections have a central vascular cylinder with xylem arranged in a star pattern, and phloem between the arms.
• Monocot root cross-sections have vascular bundles in a ring with alternating xylem and phloem.
• Eudicot stem cross-section has vascular bundles in a ring.
• Monocot stem cross-section has vascular bundles scattered throughout the stem.
• Leaf trace is a vascular bundle extending from the stem to the leaf.
• Leaf morphology: petiole connects the leaf to the stem.
• Leaf morphology: blade is the flat part of the leaf for photosynthesis.
• Sessile leaves are directly attached to the stem.
• Compound leaf morphology: leaflets are individual segments.
• Compound leaf morphology: rachis is the central stalk holding the leaflets.
• Xerophytes are adapted to dry conditions.
• Hydrophytes are adapted to aquatic environments.
• Mesophytes are adapted to moderate conditions.
• Leaf anatomy includes cuticle, epidermis, palisade mesophyll, spongy mesophyll, and vascular bundles.
• Leaf functions include photosynthesis, gas exchange, and water retention.
• Eudicot leaf vascular bundles are arranged in a reticulate pattern with bundle sheaths.
• Monocot leaf vascular bundles are scattered, without a defined pattern.
• Bulliform cells help reduce water loss by folding the leaf during dry conditions.
• Monocots have parallel venation
• Dicots have reticulate venation.