Symbiosis: Lichen, moss, John Donne « ann e michael
"A lichen is a form of plant life which results from a combination of a fungus and an alga. relationship and rarely, if ever, do they resemble either the alga or the fungus Three kinds of algae are found in lichens; brown, blue-green, and more . Hennessy New Irish Writing: August 's winning poems. Lichenology Lichen is an unnatural union between a captive algal damsel and a tyrant relationship between an algal damsel and pistachio- and jungle-green. black cauldrons used for boiling lichens could be seen outside orange, sulphur , apple green, pink and scarlet. Most grow as . It is a mutualistic symbiotic relationship; in other words both deal, but in fact the fungus needs to protect its alga.
A Visitor Learns about Lichens - Vol. 13,
Comparatively few Basidiomycetes are lichenized, but these include agaricssuch as species of Lichenomphaliaclavarioid fungisuch as species of Multiclavulaand corticioid fungisuch as species of Dictyonema. Other lichen fungi occur in only five orders in which all members are engaged in this habit Orders GraphidalesGyalectalesPeltigeralesPertusarialesand Teloschistales.
Lichenized and nonlichenized fungi can even be found in the same genus or species. TrebouxiophyceaePhaeophyceaeChlorophyceae have been found to associate with the lichen-forming fungi. One fungus, for example, can form lichens with a variety of different algae.
The thalli produced by a given fungal symbiont with its differing partners will be similar, and the secondary metabolites identical, indicating that the fungus has the dominant role in determining the morphology of the lichen. Further, the same algal species can occur in association with different fungal partners.
Lichens are known in which there is one fungus associated with two or even three algal species. In addition, periodic strong winds carry away air pollution that may come from the industrial areas of Louisiana and Texas.
And the Refuge cypress swamp is far enough away from major highways that the sulfur dioxide in car exhaust is not a problem. The many lichen species on trees in south Florida are "liking" our unpolluted air very much. It is a generalized bromeliad with roots. It has broad green spiny leaves. And it has a conspicuous flower spike that turns into the pineapple fruit that we eat.
At the other extreme is the wild Spanish moss. It is a specialized epiphyte without roots. It has scaly grey-green strands instead of leaves. And it has tiny inconspicuous flowers that mature into a tiny fruit with a few tiny air blown propagules.
The sign about Bromeliads on our Cypress Boardwalk, labeled "living off the air," is not completely accurate. They are air plants only in the sense that they have no absorptive roots. The leaf bases of the larger species trap nutrients as dust or dead plant parts are blown in the air or fall from above. And, all the species get their water and most of their mineral nutrients from rain or mist. They are also air plants. In our dry season, they have to survive in pretty dry air without rain.
Do bromeliad epiphytes help, hurt, or have no effect on trees on which they grow? What is your hypothesis about the biological interaction of epiphytes with trees on which they grow?
What is your thinking that leads to your hypothesis?
Symbiosis in lichens
What would you look for in nature that would support or reject any of these hypotheses? Look where the air plant grows on the tree. Note whether the tree or part of the tree where the epiphyte grows does well, does poorly, or is not affected compared to where the epiphyte is not present.
The easiest observations to make are with Spanish moss and ball moss since they are common. Here are three relevant photos. It is our largest but least common species.
Symbiosis: Lichen, moss, John Donne
You see, the fungus is an excellent water absorber and it also can get a grip almost anywhere, but it lacks the ability to make its own organic food. The alga, having green color just like the grass or trees, can use the energy from the sun in the manufacture of sugar. Some of this sugar goes to the fungus which in turn gives the alga a good environment in which to live.
In this way the two of them together are able to live in very difficult places such as the surface of bare rock, where neither of them could singly. In fact they are the first form of life to invade any new rock formation and to the all important first work in the breaking down of rock to soil. Do they grow anywhere else? The yellow moss on the trunk of that hemlock there is one called the stag horn lichen. Although it grows on the trees, it is in no sense a parasite.
It may get some mineral material from the dead outside bark to which it is attached, but it does not penetrate into the living tissue of the old tree and derives no organic foodstuff from the tree.
It grows equally well on living and dead trees or branches. You will notice that it doesn't grow down to the ground in very many places. This is because it doesn't do well when it is buried underneath lasting winter snows.