Types Of Root

Types of root No rfa t in b t Ka m a D2 0 0 9 1 0 3 4 6 3 5 Kh a ira t u l Hu d a Ro za ki D2 0 0 9 1 0 3 4 6 5 1 Sh a m im i At ia b t Yu s ri D2 0 0 9 1 0 3 4 6 2 7 Aid i Ezwa n i b t Ali D2 0 0 9 1 0 3 4 6 5 3

introduction • Roots are the principal water-absorbing organ of a plant.

• • They are present on essentially all vascular plants.

• • By definition, a root must have vascular tissues, water conducts in xylem and sugar conducts in phloem, arranged in a particular way.

• • Much thinner, threadlike rhizoids (means "rootlike") are present on the nonvascular plants, such as mosses and liverworts, and on gametophytes of vascular plants without seeds, such as ferns, horsetails, and club mosses.

• There are three primary functions of roots: – to anchor the plant to a substrate, – to absorb water and dissolved minerals, and – to store food reserves.

– • Typically we see roots in soil, but there are specialized types of aerial roots (air roots) that enable climbing plants and epiphytes to become attached to rocks, bark, and other non-soil substrates. 

• In addition, parasitic plants may form

• • To absorb water and dissolved minerals, a young sector of a root commonly possesses numerous single-celled projections called root hairs, which greatly increase the absorbing surface of the root and achieve much greater contact with soil particles.

• • Water uptake into the young root is rapid because there is little resistance through the outer cell walls, and in general these walls contain virtually no water-repellent wax (cutin).

• Both young and old roots can be important repositories for carbohydrates, usually in the form of starch grains located in root cortex, but in addition older roots may store massive quantities of starch and even become specialized below-ground storage organs.

• • Storage of carbohydrates in roots and other below-ground plant organs is an important plant strategy for surviving

FIBROUS ROOT • A fibrous root system (sometimes also called adventitious root system) is the opposite of a taproot system. It is usually formed by thin, moderately branching roots growing from the stem. A fibrous root system is universal in monocotyledonous plants and ferns, and is also common in dicotyledonous plants.

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• Most trees begin life with a taproot, but after one to a few years change to a wide-spreading fibrous root system with mainly horizontal surface roots and only a few vertical, deep anchoring roots. • A typical mature tree 30-50 m tall has a root system that extends horizontally in all directions as far as the tree is tall or more, but well over 95% of the roots are in the top 50 cm depth of soil.

TAP ROOT • Taproots result when the main root growing downward, the primary root, grows much larger than the secondary roots. • If you have dug up dandelions in your backyard, you've seen their taproots • . In gardens, carrots are even better taproot examples. Oak,

• At the right you see the taproot of a seedling Water Oak. The yellow line denotes where the soil's surface was when we pulled the seedling from my garden soil, so you can see that, at least in the case of this seedling, the taproot can penetrate the soil

• How tap root can beneficial to plant? – allows the plant to reach down quite far to find water to sustain itself. In drier climates, or areas where water tends to run deep, this can be incredibly useful. – Indeed, many desert plants have incredibly well-developed tap root systems, allowing them to survive in even the most arid of climates.

• Also function as a reservoir for food and water. • The tap root can grow very wide, and remain relatively protected underground, allowing the plant to save up energy for times when it may need it, such as when producing seeds. • Many plants that use their tap root as a source of food actually create tap roots that humans find appealing as well, and the so-called root vegetables are generally plants

AERIAL ROOT • You can see aerial roots on English Ivy, Poison Ivy, Trumpet Creeper,  and lots of other vines and creepers. • Aerial roots anchor climbing stems to vertical surfaces. the vine's aerial roots stick to one of the slats of a yellow-painted window shutter. The diagonal item is the vine's stem, which in real life is about the size of a small lollipop's rolled-paper handle (2 mm diameter), and you can plainly see how each tendril of the aerial root ends in a flat appendage that sticks to the slat's old paint..

Example of aerial root

• These things stick so well that when later we pulled the stem away, the roots broke but the stickers stayed stuck. Remember that here we are seeing roots arising from along the plant's stem, not at it's base. • You could follow this stem to the ground and then below the ground you'd find regular fibrous roots.

• Function – The main job of these aerial roots is to support the vine as it climbs up the window shutters, not to absorb water and nutrients. – Organs arising where they are not typically found, such as these roots arising from along a stem, are said to be adventitious

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