Morphology of Flowering Plants
- It is positively geotropic [only main root] and hydrotropic and frequently it shows negative phototropism without nodes, inter nodes, leaves, buds, flowers and fruits.
- Root cap (or) calyptra is a cap like covering over the root tip for protection against friction from soil particles.
- Root cap is absent is epiphytes, parasites, hydrophytes and mycorrhizal roots.
- The growing point is meristematic zone, where the cells are thin and non - vacuolated. Which could be otherwise called as zone of cell division / Mycorrhizal formation.
- Behind the tip is the zone of elongation, where the cells elongate rapidly
- Phloem and Xylem differentiate at root hair zone which is absent is parasitic and mycorrhizal roots.
- Bulk of the root is made of zone of maturation is root.
- A complex of one type of roots and their branches is called root system which is of 2 types - (i) Tap root system (ii) Adventitious root system.
- Tap root is a primary root which develops elongation of radicle and persist through out the life of the plant.
- Tap root bears secondary roots is an acropetal succession which also bear tertiary roots. Final root branches are called root lets which bears root caps and root hairs.
- Tap root system is of 2 types (i) Deep feeder eg : Mango, Peepal (ii) Surface feeder eg : solanum, nigrum
- To perform some secondary functions, roots undergo modifications
- Fleshy / Storage top roots.
(i) Conical - Carrot
(ii) Fusiform - Radish
(iii) Napiform - Turnip
(iv) Tuberous - Mirabilis
- In legumes, the roots bear numerous irregular swellings called nodules (or) Tubercles
- Respiratory roots (or) Pneum atophores are short, vertical and negatively geotropical roots which occur in mangrove plants, where the upper ends bear lenticels (or) Pneumathodes for exchange of gases.
- Adventitious root are common in pteridophytes and monocot and are not deep rooted. Eg : Fibrous roots : Grass, wheat.
- Fleshy adventitious roots :
(i) root tubers : Sweet potato, Tapioca
(ii) Fasciculated roots : Asparagus, Dahlia
(iii) Palmate : Orchis
(iv) Moniliform / beaded : Eg : Bitter gourd, portulaca
(v) Nodulose roots : Curcuma amada
- Pillar / prop / Columnar roots : Eg : Banyan tree
- Still roots : Sugarcane, Maize, Sorghum.
- Haustorial / Parasitic / sucking roots : Eg : Cuscata, Viscum
- Clinging / Climbing roots. Betel, Black pepper, Money plant, Ivy.
- Photosynthetic / assimilatory roots : Tinospora, podostemon, Trapa.
- Hygroscopic roots : Vanda, dendrobium.
- Epiphylbus roots : Begonia, Bryophyllum
View the topic in the video from the time 0:51 to 16:35
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