Sunday, January 13, 2008

Bryophytes


Bryophytes are plants that refer to a group of non-flowering, green plants, characterized by little or no organized vascular tissue that share a common and unique life cycle. The group comprise mosses, liverworts and hornworts of which there are at least 1500 species represented in the Indonesian flora. Bryophytes vary greatly in form, size and color. In mountain area where they are particularly abundant, they may be the most colorful element of the canopy forest flora.


The majority of bryophytes are too small to be seen by the unaided eye, but a simple lens with ten times magnification open up a whole new world of remarkable diversity and beauty. A compound microscope is required for identification of all the different species, but is unnecessary in order to gain appreciation for the range of species and basic lifestyles of many bryophytes. In appearance, mosses and liverworts are all small, green plant usually no more than a few centimeters long. These plants consist of either a leafy stern o a flat, ribbon-like body called thallus. They are anchored to the soil by long, thread-like rhizoid instead of true roots.


There are two kind reproduction of bryophytes, asexual reproduction and sexual reproduction. Mosses can readily reproduce vegetative from broken off fragments, wind disturbance or a bird collecting nesting materials are two of the many agencies which can transport pieces of bryophytes over moderate distance.


A disadvantage of vegetative, as opposed to sexual reproduction is that because the offspring are identical to the parent, adaptive genetic evolution to changing circumstances of climate or habitat is precluded. To overcome such drawback, bryophytes may also reproduce sexually. This process known as an alteration of generations, includes two generations of plants; a sporophyte phase which produces spores and a gametophyte phase, which produces male and female sex cells (gametes). In bryophytes, the gamethophyte generation which develops from asexual spores, is dominant, while the sporophyte generation is reduced. In this way the bryophytes resemble simple green algae.

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