''Jamesonia'' is a genus of
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 ...
s in the subfamily
Pteridoideae
''Pteridoideae'' is one of the five subfamilies of the fern family Pteridaceae. This subfamily contains about 14 genera and around 400 species.
Taxonomy Phylogeny
The following diagram shows a likely phylogenic relationship between Pteridoideae ...
of the family
Pteridaceae
Pteridaceae is a family of ferns in the order Polypodiales, including some 1150 known species in ca 45 genera (depending on taxonomic opinions), divided over five subfamilies. The family includes four groups of genera that are sometimes recogni ...
. It now includes the formerly separate genus ''Eriosorus''.
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Description
Species of ''Jamesonia'' are terrestrial or grow on rocks. They vary considerably in their detailed morphology. The rhizome
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...
s are short, dark brown, and creeping, with a more or less dense covering of hairs and bristles. The fertile and infertile frond
A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...
s are similar. Species show one of two different frond morphologies, related to habitat. These were formerly used to distinguish ''Jamesonia'' and ''Eriosorus'',[ but do not correspond to the evolutionary history of the species.][ Species with "''Jamesonia''-type" morphology have many fronds with short, often leathery ]pinnae
Pinna may refer to:
Biology
* Pinna (anatomy), or auricle, the outer part of the ear
* ''Pinna'' (bivalve), a genus of molluscs
* Pinna (botany), a primary segment of a compound leaf
People Surname
* Christophe Pinna (born 1968), French marti ...
, and are associated with exposed habitats. Species with "''Eriosorus''-type" morphology have fewer fronds with longer, thinner pinnae, and are associated with more sheltered areas including cloud forest
A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...
s. The stalks ( petioles and rachises) of the frond are dark brown and usually grooved on the upper (