WikiWorks at 06:44, 7 April 2007

2007-04-07T06:44:23Z

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{{Taxobox
| color = lightgreen
| name = Non-vascular plant
| image = Lunularia_cruciata.jpg
| image_width = 240px
| image_caption = A [[thallose liverwort]], ''Lunularia cruciata''
| regnum = [[Plant]]ae
| unranked_phylum = '''Non-vascular plants'''
| subdivision_ranks = Divisions
| subdivision =
Simple nonvascular plants 
  [[Green alga]]e 
Complex nonvascular plants 
  [[moss|Bryophyta]], mosses 
  [[Marchantiophyta|Hepaticophyta]], liverworts 
  [[hornwort|Anthocerotophyta]], hornworts
}}

'''Non-vascular plants''' is a general term for those plants (including the [[green algae]]) without a [[vascular tissue|vascular system]] ([[xylem]] and [[phloem]]). Although non-vascular plants lack these particular tissues, a number of non-vascular plants possess tissues specialized for internal transport of water.

Nonvascular plants have no roots, stems, or leaves, since each of these structures is defined by containing [[vascular tissue]]. The lobes (rounded parts) of the liverwort may look like leaves, but they are not true leaves because they have no [[xylem]] or [[phloem]]. Likewise, mosses and algae have no such tissues.

==Non-vascular groups==
The term non-vascular plant is no longer used in scientific nomenclature. Non-vascular plants include two distantly related groups:

* [[Bryophyte]]s - the [[moss|Bryophyta]] (mosses), the [[Marchantiophyta|Hepaticophyta]] (liverworts), and the [[hornwort|Anthocerotophyta]] (hornworts). In these groups, the primary plants are [[haploid]], with the only [[diploid]] portion being the attached [[sporophyte]], consisting of a stalk and [[sporangium]]. Because these plants lack the water-conducting tissues, they fail to achieve the structural complexity and size of most [[vascular plant]]s.
* [[Alga]]e - especially the [[green algae]]. Recent studies have demonstrated that the algae actually consist of several unrelated groups. It turns out that common features of living in water and [[photosynthesis]] were misleading as indicators of close relationship. Only the green algae are still considered relatives of the plants.

Both of these groups may be termed the "lower" plants; the term "lower" refers to these plants' status as the earliest plants to [[evolve]]. However, the term "lower" plants is not precise, since it frequently is used to include some [[vascular]] plants, the [[fern]]s and [[fern ally|fern allies]].

In the past, the term ''non-vascular plant'' included all the [[alga]]e, but also the [[fungus |fungi]] as well. Today, it is recognized that these groups are not closely related to plants, and have a very different [[biology]].

==See also==
* [[Vascular plant]]

{{plant-stub}}

[[Category:Non-vascular plants| ]]
[[Category:Plants]]

Non-vascular plant - Revision history

WikiWorks at 06:44, 7 April 2007