Botany (Stems): Exam 1

• Gymnosperms

  Have naked seeds, not enclosed in a fruit. Seeds will be carried in cones.

  
• Angiosperm

  Seeds are in fruits, and are flower bearing.Monocot and dicot

  
• Monocot

  Fibrous roots, have parallel veins, floral parts are often found in clusters of 3.Have ground tissue in replacement of a pith/cortex. Do not form true wood or cork.

  
• Dicot

  Taproot system, webbed leaves, 4-5 floral parts in clusters.

  
• Lenticels

  Loosely arranged pockets of parenchyma cells formed by cork cambium that protrude through the surface of periderm. Allows for gaseous exchange.

  
• Monocot Vascular Bundles

  The air spaces in the xylem are formed by cells that first grow then collapse to leave airspace. Phloem is composed of sieve and tube cells.There is no vascular cambium. Closed vascular bundles, surrounded by the sclerenchyma sheathe.

  
• Dicot Vascular Bundles

  Have a pith and cortex made of parenchyma.Vascular cambium found in the open bundles, produces secondary phloem on the outside and secondary xylem on the inside . Can food true wood (secondary xylem).

  
• What are vascular rays?

  Consist of parenchyma cells that function in the lateral conduction of dissolved nutrients.

  
• Spring (early) Wood


  Formed early in the season, wider in diameter compared to summer wood.

  
• Summer (late) Wood

  Dark in color, forms next to the spring wood and makes rings within the trees. Tropical trees do not usually produce any rings.

  
• Is all wood dead?

  Yes, but the sapwood helps in transport sometimes. Heart and sapwood function in support mostly.
• Does the vascular cambium produce more secondary xylem than phloem?

  Yes
• Woody Pinus Stem

  Resin canals coat a wound with resin for protection.The wood has tracheids with no fibers making it a softwood.

  
• Can wood still function if only the sapwood is removed?

  Yes, however the cutting of the all sapwood will kill the tree since it will loose nutrients.
• Rhizomes

  Horizontal stems below ground, nodes and internodes present. Runners (strawberries) are horizontal stems that grow above ground.

  
• Tubers


  Underground stems that function in food storage.

  ex: potatoes, potato eyes are nodes

  
• Bulbs


  Food storage

  ex: onions, hyacinths, tulips

  
• Corm

  Stem tissue with papery leaves

  ex: crocus, gladiolus

  
• Are thorns a stem?

  Yes, can be found on acacia trees