How doese a duckweed float?

Question

Can anybody help me find books or papers to read? For free-floating and floated-leaf plants, I know air is trapped and density is lower than water. People told me:" upper leaf surface is hydrophobic and unwettable (so it floats); and lower surface is hydrophilic". Is that true? I want to find books or papers to verifiy this. Thanks a lot

Answer 1

anyway, as u know, any leaf will float on water because the cells (mesophyl) have spaces all between them. the inside of a leaf is like a heap of baloons pressed together a little - they touch only by sides. this is to allow passage of air necessary to photosynthesis, too. the oily appearance of the "skin" , the epidermis of the leaf is good to make it last and live long and not go rotten in water. some plants that float really have one side hydrophilic and the other hydrophobic so that they dont flip the other way up, which would be undesirable. write me email if u have other questions as u study more of this

Answer 2

The Charms of Duckweed
by John W. Cross
i tried to copy some very revealing pics of this wonerful plant but couldnt ,, so u can go to this link given above and see for your self the anatomical features which help these wonderful plants in floating .
http://www.mobot.org/jwcross/duckweed/duckweed.htm

Answer 3

This link contains a newspaper article in it you should be able to print out about duckweed. Hope it helps.

Answer 4

due presence of aerenchyma cells....i.e. parenchyma cells containing huge air cavities

Answer 5

Duckweed, also known as water lentil, is the smallest flowering plant in the world. The plant consists of a short stem floating vertically in the water, roots in Spirodela and Lemna, and occasionally a flower consisting of two stamens and a pistil (some call it an inflorescence consisting of three unisexual flowers). The fruit is a utricle, a sac containing air and a seed designed to float; that of Wolffia is the smallest in the world, 0.3 mm long. Reproduction is usually by budding (as in yeast; in flowering plants, such structures are usually called runners).
The family contains four to six genera (depending on the taxonomist) and is believed to be descended from Araceae.

Floating

Floating plants may have roots hanging in the water (azolla), or anchored in the pond bottom (water lilys). Like emerged plants, this implies a vascular system and transpiration. Leaf buoyancy allows them to utilise the surface of deeper water, inward of where the taller growing edge plants would have an advantaged position in respect to sunlight, yet shallow enough to allow them to shadow the submersed.Floating plants provide shade in shallow ponds, and most accumulate on the downwind shorelines to protect the most sensitive areas from wave erosion.

Amphibious Bisort
Although not found far from the banks,and being by preference a swamp plant,
Amphibious Bisort (Polygonum amphibium) is often found covering sections of bankside water.The pretty pink flower stems are quite attractive, and bare both arial and floating leaves which are of different appearances it can sometimes be mistaken for two separate plants.The shoot system is capable of growing to great lengths over 12m (40 feet),and the plant is capable of surviving even when ponds dry out in the summer when it will temporarily become a land plant.

Azolla
This small and dainty looking plant,which in the summer is green in colour,and as exposed to increased sunlight turns red, is by nature very invasive. Sometimes called Fairy Moss even though it is a true fern, there are several variations of the species all of which have very similar characteristics in growth pattern. During winter months it appears to die back and disappear but will always return unless the winter is severe, definitely a plant to avoid introducing.

Duckweed
The Lemma family of plants often called Duckweed, are amongst the smallest of the floating plants found within the pond environment. They are extremely invasive by nature, but dislike surface disturbance of the pond, and have the ability to sink in conditions which are unfavourable, such as rain, only to reappear the following day

I vy-leaved Duckweed is the odd one out in the family, although like all the other members of the Lemma's its a totally free floating species and at the control of wind and current. It does not normally float with its leaves above the surface. It requires quiet waters and is easily out competed by the other members of the Lemma family. It rarely flowers and reproduces by vegative means. It tends to prefer waters were the nutrient levels are lower were it the thin submerged fronds are more capable of nutrient uptake than the root systems of the other Lemma's

Frogbit
The floating leaves of this plant are often found in shallow water and sheltered bays, sometimes within a growth of larger emergent plants which offer it the protection it requires. It seems to prefer calcareous waters, which may be mesotrophic or meso-eutrophic in nature. Not normally found in water much deeper than 3 feet (1 metre), it is unable to withstand dessication.

Water Hyacinth
What has to be considered one of the showiest floating plants, with leaves formed in a rosette, and the leaf petioles swollen to a extreme level which allow the plant to float with ease. The flowers are showy but fairly sparse and carried on spikes, the root system hangs below the plant between 10 & 12 inches and so offers cover for young fry and a multitude of invertebrates. It is although, extremely invasive and capable of spreading alarmingly if conditions are correct, it is unable to withstand frost conditions.

Water Lily
Everyone knows the water lilies with their large ornate flowers, and leaves which are in the form of pads which can form large clumps. There are many varieties growing in water from inches to many feet in depth. The plants forms tubur systems which are rooted well within the bottom sediments, sending out the narrow leaf stems to the pads that rest upon the surface. We will not classify them as an invasive plant as some are and some not. They offer good protection for fish and other pond animals but can be very difficult to remove if an invasive.

Another common lily is Nymphaea alba, it has the more traditional flower associated with the lilys found within the ornamental pond. A slightly more delicate plant than lutea which prefers the quieter location of backwaters and protected bays. It does quite well over various forms of substrata, and will seed quite freely. The flowers close at night and pollenation is undertaken by insects.

The fringed lily is a lowland plant often found in eutrophic waters found growing at the edge over inorganic sustrata. It tends to grow in dense masses in water from 0.5 m (18 inches) up to 2m (6 feet+). It is a rhizomatous perennial, and each flower lasts for only one day but it continues to flower over a long period. Seeds can float so the plant can easily spread, and can be invasive in areas well suited to its growth.

Water Primrose spreads out over the surface of the water from the margins with floating and aerial leaves, it also does well in damp soil in waters where evaporation receeds the water line. It does not grow well in competition with taller marginal plants where shading acts as a suppesant as well as a competitor for available resources. It tends to be mainly found in eutrophic waters prefering a higher fertility.