Скачать с ютуб Spring wood and Autumn wood Class 11 | Anatomy of Flowering Plants Class 11 Biology | NEET 2022 в хорошем качестве

Spring wood and Autumn wood Class 11 | Anatomy of Flowering Plants Class 11 Biology | NEET 2022

#Spring_wood #autumn_wood #Spring_wood_vs_autumn_wood_animation Read the article here :- https://biowizbiology.org/types-of-wood/ 0:00 Intro 0:37 Vascular cambium 1:31 Spring wood and Autumn wood 1:48 Spring wood features 2:34 Autumn wood features 3:07 Annual rings 3:47 Outro The vascular cambium is a type of meristem, and to be precise it is a lateral meristem, on the basis of its position. Being a meristem, it is made up of actively dividing cells and is responsible for formation of other tissues like secondary xylem and secondary phloem. In fact, all the tissues formed by the vascular cambium on the inner side is collectively referred as WOOD. That is, the vascular cambium forms all the different types of WOOd that we’re going to cover in this video. On the inner side of vascular cambium, you must be able to see the presence of alternating light and dark rings. These rings represents the first category of WOOD that we’re.going to see. That is the SPRING WOOD and the AUTUMN WOOD. The spring wood, as clear from its name, is formed during the spring season or early in the season so it is also called early wood It is lighter in colour and thus represented by the light brown rings in the diagram. It is also noticeable that, the thickness of the spring wood rings is more. This is because during the spring season the vascular cambium has higher activity and thus forms more amount wood. It also results, in formation of vessels having wider lumen. Lumen represent the empty spaces inside the dead cells. These wider lumen are responsible for the lower density of the spring wood. The Autumn wood is formed late in the year during autumn season and so it is also called Late wood. The colour of autumn wood is relatively dark and is represented by dark brown rings in the diagram. The lower thickness of autumn wood is due to the fact that the activity of vascular cambium is less during autumn season. The vessels of autumn wood have narrow lumen which increases the density of autumn wood. Each year a ring of Spring wood and a ring of autumn wood is formed and together they are called the annual ring. By counting the number of annual rings, we can estimate the age of the tree. However, these annual rings are distinctly visible in trees growing in temperate regions that is the regions where seasonal differences are more prominent. In tropical regions, these rings are not very distinct due to the almost constant weather throughout the year. Also these rings are not found in The wood of roots. As the age of the tree increases, more and more spring wood and autumn wood are formed by the vascular cambium. SPRING WOOD 1. Formed during the spring season. 2. Formed early in the year, therefore is also called Early wood. 3. Spring Wood is lighter in colour. 4. Rings of Spring wood are much thicker as the cambium is more active during spring season and forms more xylary elements. 5. The vessel elements of Spring wood have much wider lumen, as more transpiration occurs during spring. 6. The density of Spring wood is less. 7. The transition from Spring wood to Autumn wood is slow. AUTUMN WOOD 1. Formed during the autumn season. 2. Formed late in the year, therefore is also called late wood. 3. Autumn Wood is dark in colour. 4. Rings of Autumn wood are relatively narrower as the vascular cambium is not as active during the autumn season. 5. The vessel elements of Autumn wood have relatively narrow lumen, as the amount of transpiration is less during autumn. 6. The density of Autumn wood is high. 7. The transition from Spring wood to Autumn wood is fast. Spring wood and Autumn wood rings are not distinct in trees growing in Tropical regions due to almost constant climatic conditions throughout the year. Spring wood and Autumn wood is absent in roots. One ring of Spring wood + One ring of Autumn wood= One Annual ring. Dendrochronology- Estimating age of trees by counting the number of annual rings.