Question

Imparipinnate leaf is the one, where
(a) Leaflets are born in pairs
(b) Leaflets are small
(c) Leaflets are large
(d) The rachis is terminated by an odd leaflet

Answer 1

Hint:This type of leaf is a compound leaf and is an example of a pinnately compound leaf where leaflets are present on both sides of the common axis Rachis. These leaves are found in and found in the trees like ash, black locust, walnut, etc.

Complete answer:Imparipinnate leaves are also called odd-pinnate leaves because in these compound leaves there is an odd leaflet present in the terminal part of the rachis. This type of compound leaf looks like the figure given below –

It can be seen in the given figure that the Rachis has been terminated in a single leaflet. The other leaflets are born in pairs on the common axis along its length in the opposite directions.

Additional information: Pinnately compound leaves are of three types – even pinnate, odd-pinnate, and alternipinnate.
1. Even pinnate – in this type of compound leaves, the leaflets are born in pairs along the common axis Rachis and there are two leaves i.e. the even number of leaves in the terminal part of Rachis.

2. Alternipinnate – in this type of compound leaves, the leaflets are born on the common axis in an alternate manner in opposite directions and the Rachis terminates in a single leaflet.

So, the correct answer is ‘Rachis is terminated by an odd leaflet’.

Note:In Botany, the term pinnation is used to refer to the arrangement of the discrete plant structures like leaflets, veins, branches, lobes, or other appendages that arise at multiple points along a common axis that is commonly called Rachis. Pinnately compound leaves are found in some plants such as palms, most ferns, most cycads, etc.