Spine

A spine is a pointed outgrowth present on many plants. The equivalent adjective is " épineux".

One distinguishes several types of spine S according to the body which gave them birth by adaptation.

  • Roots spines : They are adventitious kinds of root S which one finds at certain plants épiphyte S and some Palmier S.
  • Épines caulinaire : It is about Tige S axillaires whose vegetative point fell through prematurely. The Sheet S and side buds which is dependant for him are always reduced. Strong the lignification and their great hardness makes the most frequent spines of them as bodies of protections against the Herbivore S. One finds them on many Arbre S and shrubs of the arid areas.
  • Darts : It is about an outgrowth of the cortical Parenchyme. Much less resistant than the spines caulinaires, one finds darts for example on the pinks. At the Apple tree, the dart is an undecided conical bud: if it receives much sap, it will leave to wood, if it receives little of it, it will inflate in button with flower. A dart crowned is a dart which lengthened (up to 4 cm) and ends in a button. It is not cut.
  • Sheets in spines : It is about an adaptation of the sheet whose Limbe is not developed. The Sclérenchyme is abundant and frequent lignification. One finds this adaptation for example at the berberis.
  • Stipulate spines : The Stipule undergoes the same modifications as the sheets in spines. The sheets can then preserve their role first as at the Robinier.

The spines of Cactus are characteristic. Their adaptation to the arid medium is remarkable. Their internal structure is partially hollow. Thus, the spines of cactus can be at the same time rigid and light. The vacuum contained in the spines makes it possible on the one hand to protect the plant against heat because the rays of the sun do not heat the spines as much as they would do it for a homogeneous structure and on the other hand to make penetrate condensation or rainwater for thus limiting the hydrous losses.

The persistent sheets out of needle of the Conifère S are also named spines.

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