Morphology of Flowering Plants — Important Questions

Node

Step 1: The stem is divided into segments separated by points where leaves are attached. Step 2: The point on the stem where a leaf is born (attached) is called a node. Step 3: The portion of the stem between two nodes is called an internode. Step 4: The axil is the angle between the leaf and the stem (where axillary buds are found). Step 5: The petiole is the stalk of the leaf itself, not a part of the stem. Therefore, the correct answer is node.

Reticulate venation

Step 1: Venation refers to the arrangement of veins in the leaf blade (lamina). Step 2: In reticulate venation, the veinlets form a net-like or mesh-like network. Step 3: In parallel venation, the veins run side by side parallel to each other (seen in monocots like grass, wheat). Step 4: Reticulate venation is the characteristic feature of most dicotyledonous plants. Step 5: Unicostate and multicostate are subcategories of reticulate venation but are not the basic answer expected here. The simple answer is reticulate venation.

Alternate phyllotaxy

Step 1: Phyllotaxy is the pattern of leaf arrangement on the stem. Step 2: In alternate phyllotaxy, ONE leaf arises at each node, and consecutive leaves alternate from one side to the other. Examples: China rose, mustard, sunflower. Step 3: In opposite phyllotaxy, TWO leaves arise at each node opposite each other. Examples: Calotropis, guava. Step 4: In whorled phyllotaxy, MORE THAN TWO leaves arise at each node, forming a whorl. Example: Alstonia. Step 5: Decussate is a type of opposite phyllotaxy and is not one of the three main types. The correct answer is alternate phyllotaxy.

Actinomorphic

Step 1: Flowers are classified based on the number of planes that divide them into equal halves. Step 2: Actinomorphic means the flower has radial symmetry — it can be divided into two equal halves by ANY radial plane passing through the centre. Examples: mustard, datura, chilli. Step 3: Zygomorphic means bilateral symmetry — it can be divided into two equal halves by only ONE particular vertical plane. Examples: pea, gulmohur, bean. Step 4: Asymmetric means the flower CANNOT be divided into two equal halves by any plane. Example: canna. Step 5: Unisexual refers to the sex of the flower (havin