''Alsophila decrescens'',

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

''Cyathea decrescens'', is a species of

tree fern The tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tree ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

Description

The trunk is erect, 2–3 m tall and 10–12 cm in diameter. It usually has characteristic elliptical scars caused by fallen stipe bases. Fronds are

bipinnate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

and 1–1.5 m long. The fronds may be densely pubescent and the lower pinnules are sometimes separated from the others as well as being reduced. The rachis and stipe are brown in colouration and bear narrow, dark brown

scale Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...

s. Sori are large, round and covered by fragile, brown

indusia A sorus (pl. sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (plural coenosori) is a compound sorus composed of multiple, fused sori. Etymology This New Latin word is from Ancient Gr ...

Range and habitat

''Alsophila decrescens'' is native to the rainforests of eastern and central Madagascar. Its range extends from the northern to the southern end of the island, including the Manongarivo Massif in the northwest. It inhabits moist evergreen lowland forests and

montane forests Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

on the windward (eastern) slopes of Madagascar's highlands, between 300 and 1700 meters elevation.Janssen, Thomas & France Rakotondrainibe (2008). "A revision of the indusiate scaly tree ferns (Cyatheaceae, Cyathea subgen. Alsophila sect. Alsophila) in Madagascar, the Comoros and the Seychelles". ''Adansonia'' 30 (2) - pages 221-376.

References

decrescens Endemic flora of Madagascar Flora of the Madagascar lowland forests Flora of the Madagascar subhumid forests {{alsophila-plant-stub