Thursday, April 21, 2011

Adiantum hispidulum, the maidenhair fern of southern hemisphere

In Australia they call it rough maidenhair fern and five-fingered jack, by the scraping touch of its rachis and  the pendant hand-shaped of its fronds. It is one of the most widely distributed ferns in the southern hemisphere and living in East Africa (Malawi, Kenya, Tanzania, Mozambique, South Africa, Madagascar, Comoros and Mauritius), Asia (Malaysia) and Oceania (Australia, New Zealand and some Pacific islands.) Although it prefers constant moisture and filtered light understory of tropical and subtropical forests, supports rather long periods of drought due to water accumulating in the rhizome and can live in full sun if moisture is sufficient. 

Its beauty and ease of reproduction by rhizome division have led him to be cultivated as a garden plant in every country in the world with tropical and subtropical climates. In the Macaronesian Islands has been naturalized and in a few years it has become an invasive pest ineradicable, putting endangered endemic ferns such as Asplenium azoricum, that competes for the same habitat. 

Adiantum hispidulum in a clearing in a forest of Cryptomeria japonica in the slope of the volcano Caldeira do Faial in the Azores Archipelago. Appreciate the new fronds are a beautiful pink color. Below left are some leaves of Hedychium gardnerianum feral alien.

 These specimens of Adiantum hispidulum growing between the stones of a wall that runs along the road up to the crater of the volcano Caldeira do Faial. They are surrounded by the branches of another feral alien, American Tradescantia fluminensis. 

Vigorous new Adiantum hispidulum fronds grow in a bed formed by the fronds of the fern-moss Selaginella kraussiana, too alien, on the island of Madeira. Bottom left we see several young fronds of Blechnum spicant.

Typical hand-shaped frond pendant Adiantum hispidulum. The pinnules are inserted obliquely to the rachis of the pinnae.

Underside of a frond with immature sori in early May. 

Like all ferns of the family of Adiantaceae sori are on the edge of the pinnules.

Detail of immature sori. Be seen the typical black glossy rachis all the family Adiantaceae ferns, the little stalk of each pinnules also black and the curious detail of the hairy covering of the rachis and pseudoindusium of sori. On the surface of pinnules hair is also a lesser number. These trichomes or hairs are what give the name "hispidulum" which means covered with thick hair.

Close look at the previous frond detailing rachis hairs of pseudoindusium of sori and pinnules. It is understood the reason for the name "hispidulum" that gave the botanist who described it.

Sporangium of Adiantum hispidulum with the torn and empty bag after the dispersal of spores. 

Adiantum hispidulum spores often are trilete as those in the photo, but can also be tetralete, ie a tetrahedral shape.


  1. Great again, enough inspiration to put them in rockwall conditions in my garden (zone 7)