Tag: botany

A.False – Secondary xylem formed during spring season, during the secondary growth of dicotyledonous stem is called Spring wood or early wood. It is light coloured and high density.

B.False - Secondary xylem formed during spring season, during the secondary growth of dicotyledonous stem is called Spring wood or early wood. It is light coloured and high density.

C.False – Secondary xylem formed during autumn season, during secondary growth of dicotyledonous stem is called autumn wood or late wood. It is dark coloured and high density.

D.True - Secondary xylem formed during autumn season, during secondary growth of dicotyledonous stem is called autumn wood or late wood. It is dark coloured and high density.

So, the correct option is ‘Autumn wood- dark colour, high density’.

In winter, when the cambium is less active and forms fewer xylary elements that have narrow vessels then this wood is called autumn wood or late wood. While, in spring season, cambium is very active and produces a large number of xylary elements having vessels with wider cavities, this wood is called springwood or early wood.

In dicotyledonous stems, during intra stellar secondary growth, a ring of cambium called vascular cambium is formed.  In the plants growing temperate regions, the activity of vascular cambium is influenced by the existence of maximum seasonal variations. In the spring or early summer, due to the existence of favourable conditions, a large amount of secondary xylem is formed. it is called Springwood or early wood. In the autumn season, due to the presence of unfavourable conditions, less amount of wood is formed. it is called autumn wood or latewood.  A spring wood and autumn wood together form into an annual ring. Every annual ring becomes sapwood, it is light coloured, peripheral functional wood and every sap wood gradually transform into heat wood, it is inner or central dark coloured non-functional wood contains resin clogged structures called tyloses. 

So, the correct answer is 'Duramen and alburnum'.

In coniferous gymnosperms, secondary growth takes place by the formation of vascular cambium. it produces secondary xylem or wood towards its innerside and secondary phloem or bast towards outerside. Secondary xylem, shows more number of vessels without pores. So these are called non-porous vessesl. So the wood is called soft wood or non-porous wood.

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'.

Secondary xylem is of different types is called heteroxylous wood. In this, the formation of sapwood and heartwood takes place. It is mostly found in dicotyledons.

So, the correct option is ‘Angiosperms’.

Cambium activity is influenced by the climatic changes The cambium is more active during the spring that forms plenty of xylem vessels with wider cavities also called as earlywood or the spring wood. Springwood constitutes a major part of the annual ring and occurs at the beginning of an annual ring. It contains larger and wider elements and wood is lighter in color.

Cambium activity is influenced by the climatic changes The cambium is more active during the spring that forms plenty of xylem vessels with wider cavities also called as early wood. In winter this activity slows down and gives rise to narrower xylem elements. This is the late wood or autumn wood. 

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 the spring season, cambium is very active and produces a large number of xylary elements having vessels with wider cavities and form spring or earlywood and has light colour with lower density while late or autumn wood is formed in winter and vessels are less in number with a narrow lumen which is dark in color with high density.