GDOCS NOTES

• A layer of tissue in the bark that produces cork cells to protect the tree.

  Cork Cambium
• Also known as cork, it is the protective outer layer that the cork cambium generates.

  Phellem
• A layer of parenchyma cells produced by the cork cambium inwardly; part of the periderm.

  Phelloderm
• A protective tissue that replaces the epidermis in older stems and roots, composed of the cork cambium, cork (phellem), and phelloderm.

  Periderm
• A group of plants that have hard stems and produce flowers and seeds enclosed within a carpel.

  Woody Angiosperm
• The outermost layers of stems and roots of woody plants; includes the cork cambium, cork, and phelloderm.

  Bark
• A layer of cells in a plant that produce new phloem and xylem cells.

  Cambium Layer
• The younger, softer outer portion of a tree trunk, branch, or root that functions in conduction of water and minerals.

  Sapwood
• Rings visible in the cross section of a tree trunk representing a single year's growth.

  Annual Rings
• The older, non-living central wood of a tree that is usually darker, denser, and more durable than sapwood.

  Heartwood
• The small, spongy cylindrical tissue in the center of the stem and root, often storing nutrients.

  Pith
• The inner bark of a tree, which transports nutrients downward from the leaves.

  Secondary Phloem
• Layers of protective tissue that make up the periderm:

  Periderm: Phellogen, Phellem, Phelloderm (Secondary Cortex)
• Spongy segments in the periderm that allow for gas exchange between the atmosphere and internal tissues of the stem.

  Lenticels
• Is a porous tissue made up of vast intercellular gaps between cells. 


  lenticel
• On stems and roots, it appear as elevated circular, oval, or elongated patches

  lenticel
• It allow gasses to pass between the atmosphere and the organs' interior tissues

  Lenticels
• The part of the xylem that is formed during secondary growth from the vascular cambium; makes up most of the wood of a tree.

  Secondary Xylem
• Also known as annual rings, these are layers of wood added to a tree each growing season; they can be used to estimate the age of the tree and give clues about past environmental conditions.

  Growth Rings
• A type of cell found within the xylem of flowering plants that aids in water transportation.

  Vessel Element
• Vessel elements with smaller diameters typically form during dry seasons, while those with larger diameters form during wet seasons.
• The age of a tree can be estimated by counting its growth rings, although this method is not completely reliable as not all trees produce one ring per year, and environmental factors can affect growth.


  Tree Age Estimation
• Environmental Influence on Growth Rings

  The size and characteristics of growth rings can be influenced by the weather and environmental conditions; consistent climate conditions may lead to rings of similar sizes.
• Generally has a larger diameter; associated with faster or more robust growth, often occurring in wetter seasons.

  Lighter Wood
• Typically has a smaller diameter and may be produced during slower growth periods, like in dry seasons.

  Darker Wood
• The outer layers of wood in a tree which are still involved in the transport of water and minerals from the roots to the leaves; it's the living, functional part of the wood.

  Sapwood
• The central, non-living part of a tree trunk, which is denser, darker, and more durable than sapwood; it does not conduct water and serves as support, often accumulating waste substances from the tree's biological processes.

  Heartwood
• These terms can refer to the type of wood in a botanical or practical sense.

  Softwood and Hardwood
• Botanically, softwoods come from gymnosperms which usually have needles and cones.
• Hardwoods come from angiosperms, which have leaves and produce seeds with some form of covering.
• Refers to wood from angiosperms; it is not necessarily harder than softwoods. They are often deciduous trees that lose their leaves annually and have vessel elements in their wood structure.

  Hardwood
• Though angiosperms are generally thought of when referring to hardwood, the hardest wood is from a gymnosperm, specifically the slash pine.

  Pinus elliottii (Slash Pine)
• Contrary to the association of angiosperms with hardwood, the softest commercial wood is from an angiosperm, the balsa tree.

  Ochroma lagopus (Balsa)
• Known for producing the largest individual flower in the world.

  Rafflesia arnoldii
• the largest inflorescence in the plant kingdom is Titan arum
• Unusual Secondary Growth:

  Secondary growth that does not follow the typical pattern found in most dicotyledons, possibly due to genetic variations, environmental factors, or abnormalities in the vascular cambium.
• Vascular Cambium Produces Storage Parenchyma:

  An unusual growth pattern where the vascular cambium produces large amounts of storage parenchyma cells, which are typically used for storing nutrients and water.
• A condition in which a plant has multiple vascular cambia, leading to unusual patterns of secondary growth.

  Presence of More Than One Cambium
• Variation in the growth rate and activity of the vascular cambium in different parts of the plant, which can result in irregular growth patterns.

  Differential Activity of a Vascular Cambium
• Monocotyledons, such as grasses and lilies, typically only exhibit primary growth due to the absence of a vascular cambium and thus do not undergo secondary growth.

  Monocots: Only Primary Growth