Define marginal placentation and Types of aestivation with diagram?
Answers
Answer:
Placentation is the arrangement of ovules in the ovary of a plant. The given diagram shows the types of placentation such as basal, apical, parietal, marginal, axial and free central. Marginal : One elongated palcenta is located on one side of ovary. Ovules are attached at the line of carpel's margin e.g., Legumes.
Explanation:
Marginal placentation- The ovary in which the placenta forms a ridge along the ventral suture of the ovary and the ovules develop on two separate rows is known to have marginal placentation. This type of placentation is found in peas.
Aestivation is the mode of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl.
It is divided into five main types:-
A)Valvate Aestivation:-when sepals or petals are arranged in a whorl and just touch margin of one another as seen in Calotropis.
B)Twisted Aestivation:-One margin of appendages overlaps that of the next one as seen in China rose.
C)Imbricate Aestivation:- Margin of flower overlaps but not in a particular manner as in Gulmohar.
D)Vexillary Aestivation:-When five petals differentiated into large standard petal or vexillum which overlaps two lateral petals called wings which in turn overlap the smallest anterior petals called keel and is the characteristic feature of the papilionoceae family also called as papilionaceous aestivation.
E)Quincuncial Aestivation:-When the petals are arranged in a manner that two petals are completely out of the whorl and two are completely inside while one left is half outer and half is inner side present as seen in Ranunculus.