& my world will be coloured.

Thursday, July 17, 2008

hi people!!

i am very tired and angry. first of all i hate pw. secondly i hate drill.
this sat will be the drill competition. i hate that. anyway lets not talk about all the unhappy stuff.
the following article is for all faith 1-2 pupils. its for pw.

group name: 4eva
The Roots of Mangrove Plants
Find out more about the roots of mangrove plants

Group members:
Jolene Koh Shi Yue (Leader)
Marilyn Tan Xin Wei (Questioner)
Choo Min Ming (Recorder)
Tu Ling (Newcomer)
Ronald Bay (Photographer)
Gan Man Hua (Encourager)

INTRODUCTION ON PROJECT:
We wanted to find out more about the roots of the mangrove plants and how these roots can help the plants to survive.

CONTENT:
Roots are the part of mangrove trees. They are very important to the trees as they are used to provide support for the trees in unstable soils. When storms come, they also withstand the currents coming into the mangrove area. Some roots are used to take in air for the plants. Their growth is one of the functions of apical meristem located near the tip of the roots. Not only that, they also help the mangrove trees to transport water and nutrients to all parts of the plant. Mangrove roots can be classified into four types ------ aerial roots, prop roots, kneed roots and plank roots. Each type of root has different shape, size and function. Now let’s take a trip to find put more about them and how important they are in the nature.

Aerial roots
Aerial roots are roots that are above ground. In Avicennia species, the pneumatophores are erect side branches of the horizontal roots which grow just below the soil. They are pencil-like and grow up to only 30 cm tall. They are almost always adventitious. They are found in diverse plant species, including epiphytes also known as air plants, which includes the orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan tree, the warm-temperate rainforest rātā and pōhutukawa trees of New Zealand and vines like English ivy and irritating poison ivy. These specialized aerial roots enable plants to breath air in habitats that have waterlogged soil. The roots may grow down from the stem, or up from typical roots. Some botanists classify these as aerating roots rather than aerial roots, if they come up from soil. The surface of these roots are covered with lenticels which take up air into spongy tissue which in turn uses osmotic pathways to spread oxygen throughout the plant as needed. This plant organ that is found in so many diverse plant families has different specializations that suit the plant habitat. In general growth form, they can be technically classed as negatively gravitropic (grows up and away from the ground) or positively gravitropi (grows down toward the ground.)

Kneed roots
Among the Bruguiera species, the horizontal roots growing just below the soil surface periodically, grow vertically upwards then immediately loop downwards to resemble a bent knee. By repetition, a single horizontal root develops a series of knees at regular intervals. The aerial portions (kneed) of these roots help in aeration of the whole root which because it spreads so widely, improves anchorage in the unstable mud. Lumnitzera species also produce inconspicuous, small kneed roots which appear to be intermediate in structure between Avicennia and Sonneratia species. Some trees, such as Bruguiera and Ceriops have "kneed-roots", horizontal roots growing just below the soil surface grow vertically upwards and then immediately loop downwards to resemble a bent knee. Tumu is the most widely distributed of the Rhizophoreae family.The kneed roots of the plant comprise a sponge-like system of air chambers and tubes which acts as an air reservoir when the roots are submerged. The pneumatophores are covered with many lenticels which allow air but not water to enter the root.

Prop roots
Prop roots are adventitious support roots, which are common among mangroves. They grow down from lateral branches, branching in the soil. The plants that have these roots is easily identified by its tangled, reddish roots called "prop-roots". These roots have earned mangroves the title, "walking trees". This mangrove, in particular, appears to be standing or walking on the surface of the water. Rhizophora mangle grows on prop roots, which arch above the water level, giving stands of this tree the characteristic "mangrove" appearance. Unlike stilt roots, these roots are of uniform thickness and flexibility and will not root on reaching the ground. They, however, lend support to the tree. They are adventitious roots that develop on a trunk or lower branch that begin as aerial roots (another example; reaching for the water) but eventually grow into a substrate of some type; these roots in some cases seem to provide mechanical support, having either good compression or tensile properties to help support trees at their bases. In Bakau (Rhizophora species), branched, looping roots arise from the trunk and lower branches. Prop roots that are in Rhizophora species, Avicennia species and Acanthus ilicifolius are unbranched adventitious roots growing downwards from branches or the canopy to the bottom.

Plank roots
Plank roots are another kind of roots that is found in mangrove helps certain plants to breathe. They are usually found in wet areas. The trees are 3-8 m tall; buttresses long and snaking laterally; bark light brown, yellowish or greenish, smooth, flaking off. They have a special name, “Xylocarpus granatum”; the horizontal roots grow vertically upwards on the upper side for the entire length. They also curve in a snake like fashion so wavy, plank-like structures radiate outwards from the trunk base. The exposed vertical portions help in aeration and the widely spreading roots help improve anchorage in the unstable mud. Gas exchange and oxidation at the root surface may help to avoid contacts with the toxins. In mangroves it is made possible by the presence of oxygen flux at the spongy tissue with large air spaces found between the cells of the stems and leaves of aquatic plants (aerenchyma). The plank roots have massive roots that grow rapidly penetrating the peat substrates and form spreading anchor into it. Some older plants will likely have built big and strong buttresses to support the plants. So plank root is quite important to quite a lot of plants in the mangrove.

The above are the information of the four different types of roots. To date, there are more than these 4 species of roots. Some of these roots are undiscovered by humans. Maybe they are unnoticeable or unattractive but they will wait for us to find out more about them. Finally, through this report, we believe you had learnt more about the roots and hope all of you had enjoyed it.

ok thats all :) enjoy your day. :)

(Your Name) ♥ 8:16 PM