Taxonomy

Lepisorus clathratus

Rhizome scale of Lepirosurs clathratus © Li Wang

Lepisorus clathratus has the following synonyms:

  • Polypodium clathratum (C B Clarke)
  • Polypodium papakense (Masamune)

Lepisorus clathratus is a polypod fern which belongs to the Polypodiaceae family and the Lepisorus genus. The genus Lepisorus is a taxonomically difficult genus due to the morphological similarity of its species. In addition, the systematic position of Lepisorus was not clear until Ching (1933) raised it to generic rank based on morphological distinctness.

Recent phylogenetic analyses recovered Lepisporus clathratus as a distinct lineage within the genus Lepisorus. It is still not clear if the lineage comprises a single species Lepisorus clathratus, or several closely related and morphological highly similar species.  

The phylogenetic studies also confirmed that Lepisorus clathratus includes individuals with regular dehiscent sporangia and individuals with indehiscent sporangia - previously, the latter were treated as the segregate genus Platygyria.

Morphology

The leaves are:

  • simple and entire
  • elliptical or lanceolate
  • green in summer

The leaves have veins that are visible on both surfaces, but not prominent.

The rhizome is:

  • long-creeping
  • covered with concolored, clathrate scales - consisting of large clear lumina with long-protruding teeth on the margin

The sori are:

  • round
  • large
  • form 2 straight lines between midrib and margins

Paraphyses cover the young sori. They are irregular or even ovate-lanceolate and usually fall off when sori are mature.

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Glossary
Dehiscent

Plant structures that open at maturity.

Epiphytic

Grows on another plant or structure, but does not derive nutrition from it.

Indehiscent

Plant structures, such as fruits that do not open at maturity.

Ovate-lanceolate

Having a shape between oval and lance-like.

Paraphyses

Erect sterile filaments occurring amongst reproductive organs in plants.

Segregate genus

A segregate genus is created when a genus is split off, from another genus.

Sori

Clusters of sporangia.

Sporangia

Spore producing structures.

Water stress

Occurs when the demand for water exceeds the available amount during a certain period.