bot #8

• axil - the angle formed by the stem and the leaf
• such buds are called;

  • leaf buds
  • flower buds
  • mixed buds
• stem - refers to the plant axis that bears buds and shoots w leaves and, at its basal end, root
• the stem conducts water and nutrient minerals from their site of absorption in the roots to the leaves by means of certain vascular tissues in the xylem
• the movement of synthesized foods from the leaves to other plant organs occur chiefly though other vascular tissues in the stem called phloem
• node - the place from where the lanes grow. is a point on the stem from which leaves/buds arise
• internode - the space between 2 nodes.
• bud - an embryonic stem that has the potential for further plant growth.
• axillary - a bud that grows in the axil
• apical - a bud that grows in the apical position of the stem/branch
• as a result of injury, adventitious buds may be formed also in the internode of the stems, in leaves, or roots.
• the growing portion at the apex of the shoot is the terminal bud
• types of stem;

  • aerial
  • sub-aerial
  • underground
• aerial - erect, rigid, strong and upright as in herbs, shrubs and trees
• sub-aerial - weak, unable to stay upright and trail on ground as creepers or climb up as climbers
• underground - buried in soil and produces aerial branches under favourable conditions only
• underground modified stem;

  • rhizome
  • corm
  • bulb
  • tuber
• rhizome - thick, fleshy, flattened horizontally growing stem near the soil surface. bears scale leaves on nodes, terminal and axillary buds, adventitious roots
• corm - fleshy, spherical stem w flattened base, grows vertically; bears many scale leaves, distinct nodes and internodes, buds & adventitious roots
• bulb - reduced, flattened discoid stem w crowded nodes bearing overlapping fleshy (inner) and dry (outer) scale leaves. terminal bud forma foliage leaves. adventitious roost grow from discoid base
• tuber - swollen tips of underground lateral branches of stem, store food as starch, bear eyes. each eye is a node which bears bud and scar of scale leaves
• underground : rhizome

  
• underground : rhizome

  
• underground (saffron) : corm

  
• underground (gladiolus) : corm

  
• underground (yam) : corm

  
• underground (onion) : bulb

  
• underground (potato) : tuber

  
• stem dicot

  
• sub aerial stems

  • runner
  • stolon
  • offset
  • sucker
• runner - long, weak, slender branch w long internodes. runs horizontally on soil surface giving off adventitious roots at nodes
• sub aerial (grass) : runner

  
• sub aerial (oxalis) ; runner

  
• stolon - weak lateral branch which grows upwards then arches down to meet the soil, strike roots and produce daughter plants
• sub aerial (mint) ; stolon

  
• sub aerial (jasmine) ; stolon

  
• offset - runner but thicker and shorter, grow for a short distance then produce cluster (rosette) of leaves above and adventitious roots below; generally aquatic plants
• sub aerial (water hyacinth) ; offset

  
• sub aerial (water lettuce) ; offset

  
• sucker - underground runner which grows horizontally for a distance under soil then emerges obliquely upwards, strikes roots and form daughter plants