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

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another 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 epiphyt ...

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 Originally, three or four groups of plants w ...

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

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

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 Glossary ...

, 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 b ...

, with a triangular-shaped core of

xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...

. 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 un ...

s. Small stalks end with simple

sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

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 * Bifid ...

, rounded

sporophyll In botany, 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 megasp ...

s. Bean shaped, monolete

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

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

ammonium Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) polyatomic ion, molecular ion with the chemical formula or . It is formed by the protonation, addition of a proton (a hydrogen nucleu ...

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

{{fern-stub Psilotaceae Flora of the Nicobar Islands Epiphytes Taxa named by Olof Swartz