Raffi at 04:58, 8 April 2007

2007-04-08T04:58:59Z

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The '''bryophytes''' are those [[embryophyte]] [[plant]]s ('land plants') that are [[non-vascular plant|non-vascular]]: they have tissues and enclosed reproductive systems, but they lack [[vascular tissue]] that circulates liquids. They neither [[flower]] nor produce [[seed]]s, reproducing via [[spore]]s.

== Bryophyte classification ==

The bryophytes do not form a [[monophyletic group]] but consist of three groups, the '''Marchantiophyta''' ([[Marchantiophyta|liverwort]]s), '''Anthocerotophyta''' ([[hornwort]]s), and '''Bryophyta''' ([[moss]]es).

[[Image:Bryo_cladogram.jpg|thumb|556px|center|Two hypotheses on the phylogeny of land plants (embryophyta).]]

Modern studies of the land plants generally show one of two patterns. In one of these patterns, the liverworts were the first to diverge, followed by the hornworts, while the mosses are the closest living relatives of the polysporangiates (which include the vascular plants). In the other pattern, the hornworts were the first to diverge, followed by the vascular plants, while the mosses are the closest living relatives of the liverworts. Originally the three groups were brought together as the three classes of division '''Bryophyta'''. However, since the three groups of bryophytes form a [[paraphyletic]] group, they now are placed in three separate divisions.

== Bryophyte sexuality ==

These plants are generally [[gametophyte]]-oriented; that is, the normal plant is the [[haploid]] gametophyte, with the only [[diploid]] structure being the [[sporangium]] in season. As a result, bryophyte sexuality is very different from that of other plants. There are two basic categories of sexuality in bryophytes:

* [[Dioicous]] bryophytes produce only [[antheridium|antheridia]] (male organs) or [[archegonium|archegonia]] (female organs) on a single plant body.
* [[Monoicous]] bryophytes produce both [[antheridium|antheridia]] and [[archegonium|archegonia]] on the same plant body.

Some bryophyte species may be either monoicous or dioicous depending on environmental conditions. Other species grow exclusively with one type of sexuality.

Notice that these terms are ''not'' the same as '''monoecious''' and '''dioecious''', which refer to whether or not a [[sporophyte]] plant bears one or both kinds of gametophyte. Those terms apply only to [[Spermatophyte|seed plants]].

== See also ==
* [[Embryophyte]]
* [[Marchantiophyta]] (liverworts)
* [[hornwort |Anthocerotophyta]] (hornworts)
* [[moss |Bryophyta]] (mosses)
* [[Plant sexuality]]

== References ==
{{Wikisource1911Enc|Bryophyta}}
* Chopra, R. N. & Kumra, P. K. (1988). ''Biology of Bryophytes''. New York: John Wiley & Sons. ISBN 0-470-21359-0.
* Crum, Howard (2001). ''Structural Diversity of Bryophytes''. Ann Arbor: University of Michigan Herbarium. ISBN 0-9620733-4-2.
* Goffinet, Bernard. (2000). Origin and phylogenetic relationships of bryophytes. In A. Jonathan Shaw & Bernard Goffinet (Eds.), ''Bryophyte Biology'', pp. 124-149. Cambridge: [[Cambridge University Press]]. ISBN 0-521-66097-1.
* Oostendorp, Cora (1987). ''The Bryophytes of the Palaeozoic and the Mesozoic''. Bryophytorum Bibliotheca, Band '''34'''. Berlin & Stuttgart: J. Cramer. ISBN 3-443-62006-X.
* Prihar, N. S. (1961). ''An Introduction to Embryophyta: Volume I, Bryophyta'' (4th ed.). Allahabad: Central Book Depot.
* Raven, Peter H., Evert, Ray F., & Eichhorn, Susan E. (2005). ''Biology of Plants'' (7th ed.). New York: W. H. Freeman and Company. ISBN 0-7167-1007-2.
* Schofield, W. B. (1985). ''Introduction to Bryology''. New York: Macmillan. ISBN 0-02-949660-8.
* Watson, E. V. (1971). ''The Structure and Life of Bryophytes'' (3rd ed.). London: Hutchinson University Library. ISBN 0-09-109301-5.

[[Category: Bryophytes]]

Bryophyte - Revision history

Raffi at 04:58, 8 April 2007