NAT SCI Plant Tissues

• Ground Tissue System - includes all tissues that are neither dermal nor vascular
• Three Types of Ground Tissue System: Parenchyma, Collenchyma, Sclerenchyma
• Cortex, Pith - site of occurrence in the plant body for parenchyma
• Examples of Plastids: chloroplast, leucoplast, chromoplast
• Surface fibers: grow from the surface of seeds (cotton), leaves, or fruits (coconut coir
• Cortical fibers: as the name implies, originate in the cortex
• Xylary Fiber: also called wood fiber, part of xylem and is the longest xylem elements
• Osteosclereids: bone shaped, elongated with swollen ends
• Dermal tissue covers the plant body and is consists of epidermis.
• If guard cells lose water and shrink, they straighten, closing the stomatal pore.
• Cell Type of Epidermis: Ground cells, Guard cells, cells forming Trichomes, Sclerenchyma cells
• site of occurrence in the plant body of periderm (in trees) - outer layer, mainly stems
• Phloem - transports carbohydrates from leaves to other parts of the plant.
• annular thickening (annular secondary wall) - small amount of secondary wall, organized set of rings
• Reticulate Thickening (reticulate secondary wall) - secondary wall is deposited in the shape of a net
• PITs - found in the side walls for the lateral transfer of water through pitpairs
• All angiosperms have sieve tube members, but none of the nonangiosperms has them
• Sieve cells are associated with albuminous cells.
• Sieve tube members are controlled by companion cells.
• The xylem of a vascular bundle is PRIMARY XYLEM.'
• The vascular bundle phloem is PRIMARY PHLOEM
• In basal angiosperms and eudicots, vascular bundles are arranged in one ring surrounding the pith, a region of parenchyma similar to the cortex.
• Meristem from Greek Word ‘Meristosis’ meaning to divide
• three main types of meristematic tissue: Apical meristem, Intercalary Meristem, and Lateral Meristems
• Protoderm - give rise to epidermis
• Bark: cork cambium -> cork cells of outer bark
• Year rings: secondary xylem
• Cold winter or hot dry conditions - > slow growth -> small xylem (narrow and thick walled)
• Protoderm – The meristem that always differentiates into protective structures - epidermis.