''Psilotum complanatum'', the flatfork fern, is a rare herbaceous

epiphytic An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...

fern ally in the genus ''Psilotum''. There is some evidence that it might be a true

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except ...

that has lost some typically fern-like characteristics. Morphologically, the plant is simple, lacking leaves and roots, and having hanging stems with

dichotomous branching This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Gloss ...

, which lack developed leaves but have minute scales. The stems and branches have

protostele In a vascular plant, the stele is the central part of the root or stem containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue (pith) and a pericycle, which, if present, defines the outermost bo ...

, with a triangular-shaped core of

xylem Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived fr ...

. 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 Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be u ...

s. Small stalks end with simple

sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...

from the axils of minute

bifid Bifid refers to something that is split or cleft into two parts. It may refer to: * Bifid, a variation in the P wave, R wave, or T wave in an echocardiogram in which a wave which usually has a single peak instead has two separate peaks * Bifi ...

, rounded

sporophyll A sporophyll is a leaf that bears sporangia. Both microphylls and megaphylls can be sporophylls. In heterosporous plants, sporophylls (whether they are microphylls or megaphylls) bear either megasporangia and thus are called megasporophylls, or m ...

s. Bean shaped, monolete

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...

s are produced. The spores germinate best in a dark environment when

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternar ...

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. ''Psilotum complanatum'' lives in moist evergreen forests on the Malay Peninsula, Australia, Fiji islands, Mexico, Hawaii 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.PlantNET - FloraOnline
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References

{{Taxonbar, from=Q2013154 Psilotaceae Flora of the Nicobar Islands Epiphytes Taxa named by Olof Swartz