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Ripe   [ Botany ]
Synonym: Mature
Adjective - noun: Ripening
Transitive and intransitive verb: To ripen  (past Ripened, past participle Ripened, present participle Ripening, 3rd person present singular Ripens)

Dictionary of botanic terminology
 index of names

   Of a fruit fully developed or mature.  

Ripening or maturation is a process in fruit that causes them to become more edible. In general, fruits get sweeter, less acidic, less green and softer as they ripen. 
After a process known as pollination the petals of the flower fall off , the ovary begins to expand and the ovule begins to develops into a seed. The ovary eventually comes to form, along with other parts of the flower in many cases, a structure surrounding the seed or seeds that is the fruit.

Stages of ripening/maturation are regulated by phytoregulators (hormones).
At first the developing seeds inside the ovary wall start to produce cytokinins which are hormones that are secrete by the seed and cause cell division in the ovary wall that begins to expand.
Next, the growing seeds produce gibberellic acid which is exported to the wall of the ovary and causes rapid expansion of each of the cells. The combination of more cells and expanding cells leads to tremendous increase in the size of the ovary. As this is happening, the mother plant is producing another hormone, abscisic acid, which causes the embryo in the developing seeds to become dormant. This is adaptive because it prevents the seed from sprouting inside the warm, moist fruit. Fruit development continues until the seeds have achieved a complete ripening.
An other important plant hormone involved with ripening is the chemical ethylene. Ethylene is a gas created by plants at the final stage of maturation. Ethylene causes increased levels of certain enzymes in the fruit. These enzymes include:
• amylase, which breaks down starch to produce simple sugars.
• pectinase breaks down pectin, the substance that keeps fruit hard.
• Other enzymes break down the green pigment chlorophyll, which is replaced by other coloured pigments such as blue, yellow or red.
This sequence of events is diagrammed below:

With some multi-seeded fruits the extent of development of the pulp of the fruit is proportional to the number of fertilized ovules. The wall of the fruit, developed from the ovary wall of the flower, is called the pericarp or fruit wall.






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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