Botany and Plant Science

In many dioecious species, the application of auxins like IAA (Indole-3-acetic acid) can induce the development of male flowers on genetically female plants by altering hormonal balance.

In certain plants like Strychnos, anomalous secondary growth occurs where the cambium produces phloem islands within the xylem, a phenomenon known as interxylary phloem.

The inner or central dark coloured non-functional wood or secondary xylem formed during secondary growth in dicot stem is called Heartwood or duramen.

So, the correct option is ‘Inner part of secondary xylem’.

The large sized, slightly raised sports or aerating pores present in the cork tissue or are called Lenticels. These are the patches on the surface of the bark. These are found in old dicotyledonous stems. These are formed in the place of stomata. They have outer raised margins and internally, loosely arranged colourless parenchyma cells are present, called as complementary cells, These are meant for gaseous exchange.

Secondary xylem consists of large-sized vessels and tracheas. Their cell walls are thickened by lignin deposition and it provides excellent mechanical support to the plant. This thicken deposition is the wood of the plant and it is used for making timber.

Secondary growth is characterized by an increase in thickness or girth of the plant, and is caused by cell division in the lateral meristem, which are lacking in herbaceous plants. Lateral meristems include the vascular cambium and, in woody plants, the cork cambium.

In dicotyledonous stems, during intra stelar secondary growth, a ring of cambium called vascular cambium is formed.  Vascular cambium produces more amount of secondary xylem towards its innerside, and less amount of secondary phloem towards innerside. In the plants growing temperate regions, the activity of vascular cambium is influenced by existence of maximum seasonal variations. In the spring or early summer, due to the existence of favorable conditions, large amount of secondary xylem is formed. it is called Springwood or early wood. It is lighter in colour with low density. In the autumn season, due to the presence of unfavorable conditions, less amount of wood is formed. it is called autumn wood or late wood. It is darker in colour with higher density.

So, the correct answer is 'Depends on season and region where the plant grows'.

Some of the dividing pericycle cells are committed to the asymmetric, formative divisions that give rise to lateral root primordia and lateral root formation. The endodermis is the central, innermost layer of cortex in some land plants. It is made of compact living cells surrounded by an outer ring of endodermal cells with hydrophobic substances (Casparian Strip) to restrict the apoplastic flow of water to the inside. Sapwood is the soft outer layers of recently formed wood between the heartwood and the bark, containing the functioning vascular tissue and not central, dark colored, non-conducting part of secondary xylem.

 In a typical monocot root, Epiblema is single layered, consists of thin- walled cells. A few tubular root hair arise as unicellular elongation of epiblema cells.

The epidermis is a single-layered group of cells that covers plants leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds, and especially in roots absorbs water and mineral nutrients. 

A cuticle is the waxy layer present on the epidermis of a young stem which generally curtails the water loss by transpiration.

The epidermis cells are the cells which form the outer layer and plays an important role in protection. It helps to prevent the water loss by transpiration. Nerium, is a xerophyte which has layers of epidermal tissue to curtail the rate of transpiration. It is a type of xerophytic adaptation.
Thus, the correct answer is option D.

Laticiferous vessels are the specialized thin walled parenchymatous cells that secrete latex and are found in the cortex. They lack pits and are composed of cellulose and hemicelluloses and serve to secrete latex. Epidermis is the outermost covering of the primary plant body and is mostly represented by a single layer of compactly arranged, barrel-shaped parenchyma cells.
The innermost layer of cortex forms endodermis which has compactly arranged barrel shaped cells. The primary thin walled endodermis shows suberin deposition in form of bands or strips that run around the radial and end walls of the cells and forms casparian strips. Vascular bundle consists of xylem, phloem and cambium (in dicot only) which are derived from procambium and serve in translocation of food and sap.
Thus, the correct answer is option A.