Psilotum complanatum
Encyclopedia
Psilotum complanatum 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.
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 their length and are covered with brownish colored hair-like rhizoid
s. Small stalks end with simple sporangia from the axils of minute bifid, rounded sporophyll
s. Bean shaped, monolete spore
s are produced. The spores germinate best in a dark environment when ammonium
is present. The gametophyte is non-photosynthetic, living in association with a fungus for its nutritional needs. Plants grow from a subterranean rhizome which anchors the plant in place and absorbs
nutrients 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.
Fern ally
Fern allies are a diverse group of seedless vascular plants that are not true ferns. Like ferns, a fern ally disperses by shedding spores to initiate an alternation of generations.-Classification:...
in the genus Psilotum. There is some evidence that it might be a true fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
that has lost some typically fern-like characteristics.
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
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...
. 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 their length and are covered with brownish colored hair-like rhizoid
Rhizoid
Rhizoids are thread-like growths from the base or bottom of a plant, found mainly in lower groups such as algae, fungi, bryophytes and pteridophytes, that function like roots of higher plants ....
s. Small stalks end with simple sporangia from the axils of minute bifid, rounded sporophyll
Sporophyll
A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls bear either megasporangia , or microsporangia...
s. Bean shaped, monolete spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s are produced. The spores germinate best in a dark environment when ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
is present. The gametophyte is non-photosynthetic, living in association with a fungus for its nutritional needs. Plants grow from a subterranean rhizome which anchors the plant in place and absorbs
nutrients 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.