''Jamesonia'' is a genus of
ferns 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. 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 shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
s are short, dark brown, and creeping, with a more or less dense covering of hairs and bristles. The fertile and infertile fronds 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, 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 (TMCF), is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud c ...
s. The stalks ( petioles and rachises) of the frond are dark brown and usually grooved on the upper ( adaxial) surface. The sori occur along the veins of the segments of the fronds or are sometimes spread more widely on the lower (