Plant Growth and Development

(a) Senescence : Senescence is the process of  ageing in plants. It is the period between maturity and death.

(b) Abscission: It is the natural falling of leaves, foliage branches, fruits, floral parts etc.  

(c) Quiescence : It is the suspension of growth due to external factors. It is a period during which development is suspended. 

(d) Vivipary : It is the process when seeds germinate inside fruits which are still attached to the mother plant. 

Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedling.

Auxins are of two types :

(1) Natural auxins : These are naturally occuring auxins, isolated from plants and are regarded as phytohormones e.g. IAA. NAA etc.

(2) Synthetic auxins : These are synthesized by artificially e.g. IBA 2,4-D etc.