Psilotum complanatum

Taxobox
name = "Psilotum complanatum"


image_width =
image_caption =
regnum = Plantae
divisio = Pteridophyta
classis = Psilotopsida
ordo = Psilotales
familia = Psilotaceae
genus = "Psilotum"
species = "P. complanatum"
binomial = Psilotum complanatum
binomial_authority = Sw.

"Psilotum complanatum" (Flatfork Fern) is a rare herbaceous epiphytic fern ally in the genus "Psilotum". There is some evidence that it might be a true fern that has lost some typically fern-like characteristics. [cite journal| last=Qiu | first=Yin-Long | coauthors=Jeffrey D. Palmer | year=1999 | month=January | title=Phylogeny of early land plants: insights from genes and genomes | journal=Trends in Plant Science | volume=4 | issue=1 | pages=26–30 | doi=10.1016/S1360-1385(98)01361-2] Morphologically, the plant is simple, lacking leaves and roots, and having hanging stems with dichotomous branching, which lack developed leaves but have minute scales. The stems and branches have protostele, with a triangular-shaped core of xylem. The scales are arranged in two rows along the flat stems and branches. The stems are broadly triangular in cross section and 5 mm wide. The branches are 1.5 to 2 mm wide. "P. complanatum" grows 10 to 75 cm long and stems branch in pairs a number of times up there length and are covered with brownish colored hair-like rhizoids. Small stalks end with simple sporangia from the axils of minute , rounded sporophylls. Bean shaped, monolete spores are produced. The spores germinate best in a dark environment when ammonium is present.cite journal| last=Chuahan | first=Nidhi | coauthors=Hitendra Padalia, Stutee Gupta, M. C. Porwal, and P. S. Roy | year=2003 | month=July | day=25 | title="Psilotum complanatum" Sw., a rare epiphytic fern ally of Great Nicobar Island: Exploration and habitat monitoring | journal=Current Science | volume=85 | issue=2 | pages=193–197 | url=http://www.ias.ac.in/currsci/jul252003/193.pdf | accessdate=2008-03-15] The gametophyte is non-photosynthetic, living in association with a fungus for its nutritional needs. [ [http://www.esu.edu/~milewski/intro_biol_two/lab_2_moss_ferns/Psilophyta.html Psilophyta ] ] Plants grow from a subterranean rhizome which anchors the plant in place and absorbsnutrients by means of filament like rhizoids.

Some Botanists believe "P. complanatum" is a survivor from a very primitive lineage of fern-like vascular plants.

"P. complanatum" lives in moist evergreen forests on the Malay Peninsula,South Australia, Fiji islands, Mexico and South America. In India it is reported only from the Nicobar group of islands. Plants are typically found hanging from the trunks of trees or other epiphytic plant species. [ [http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Psilotum~complanatum PlantNET - FloraOnline ] ]

References