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Plant  [ Botany ]

Dictionary of botanic terminology - index of names

     
  A plant is a member of the kingdom Plantae, it is a multicellular and eukaryotic living organism which life cycle consists of alternating sexual and asexual generations. Plant also undergoes photosynthesis.  
     
One of most important characteristic of plants is that they undergo photosynthesis which is that they use the energy of the sun to convert water and carbon dioxide into food (sugars) and oxygen by means of chlorophyll and carotenoid pigments; it stores food in the form of starch.
A plant has cellulose cell walls; it lacks centrioles, which are structures involved in cell division in animals. It usually cannot move of its own accord. The ancestors of modern plants evolved in the seas nearly 700 million years ago. Another 265 million years passed before the first plants appeared on land. Possibly exist nearly 300,000 different species of plants. Containing the
• Bryophytes (small plant lacking vascular tissue and lacking true roots, stems, and leaves)
• Mosses (small plants forming green carpets consisting of a stem like-axis with small leaf-like),
• Liverworts (grow close to the ground with lobed which resemble lobes of liver)
• Seedless Vascular Plants (lycopods, horsetails, and ferns)
Seed Producers including Gymnosperms which have no flowers (conifers, cycads, ginkgos, and Welwitschias) and Angiospermae the flowering plants in which the seeds are enclosed in a fruit that develops from the ovary of the flower.

 

Angiosperms are divided into two subclasses: Dicotyledonae (with two seed leaves (cotyledons) and branched leaf vein) Monocotyledonae. (with one seed leaf and parallel leaf veins)
Plants grows almost everywhere on Earth from the tundra to the rainforest, in the desert and in the water the only places without plants are the polar and high altitude land, the really arid deserts, and the deep ocean.

 


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Holdfast roots  [ Botany  ]

Dictionary of botanic terminology - index of names

 
     
  Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.  
     
Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans),  develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994
     

 

 

 

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