Actinostachys
Actinostachys (Wall.), informally known as the ray ferns, is a genus under the family Schizaeaceae with a total of thirteen species, one of which is native to Western Australia, the Actinostachys digitata (Wheeler, 1998; Chinnock, n.d.). Actinostachys was originally included within the genus Schizaea, however, it became segregated due to the flabelliform (fan-shaped) frond blade (eol, 2014). Actinostachys is a terrestrial perennial fern that has an upright growth habit (Wheeler, 1998). This genus thrives in tropical and subtropical regions; the species native to Australia can be located in the Kimberly region of WA, as well as the Northern Territory and the Queensland Ranges (Wheeler, 1998; DPAW, 2014).
Not much is known about the conservation of the genus of Actinostachys within Australia, as there is only one species, the Actinostachys digitata, that is native to Western Australia, and all information available is on that species. Actinostachys digitata has been given the conservation code of a priority two species by the Department of Parks and Wildlife (DPAW, 2014; DPAW, 2014), This means that it is a poorly known species, with few collections or sight records, this species is not currently threatened or endangered within WA (DPAW, 2014).
Although not much is known on the threats to Actinostachys in WA, some threats that may impact this genus include; vulnerability to fire, as over 70% of West Australian adult species will die if exposed to a high amount of leaf scorching (Smith, 2004), damage from invasive flora and fauna species and competition from intrusive, exotic species of flora for space and nutrients. Known problems for other species of Actinostachys, outside of Australia include; damage by invasive fauna, herbicide leaching, the clearing of land and the invasion of exotic flora species (Pynee, Grangaud, & Rouhan, 2011).
The genus of Actinostachys are small land based ferns that live for multiple years before dying out, with only one species native to Western Australia. Generally, the genus of Actinostachys are small ferns, however, as dimensions differ between species it is not possible to give a genus size, the species of Actinostachys digitata are between 0.09 and 0.2 metres high (DPAW, 2014). The rhizome structure is usually short and in either an upright position or it will creep horizontally along the ground; the epidermal surface is comprised of scales and young rhizomes are covered in small, brown, multicellular hairs. Fronds (leaves or the leaf-like part on a fern) on the Actinostachys are generally tufted, and grow out from the stem in a fan-shaped formation, the leaflets that make up each frond are branched in a simple or dichotomous (divided into two parts) arrangement. The stem of each frond, also known as the stipe, is short, and it continues into the frond’s ‘blade’, the collection of leaflets contained on each frond, also known as a lamina. The blade is straight, and each individual leaflet coming off the stem is also straight and flattened, almost grass-like in appearance, with a smooth and slightly shiny texture. Each fertile frond contains 2 or 4 rows of sporangia on either side of the major vein (costule), which are located on small, tufted, straight blades called sporophores connected to the leaflets. The spores are produced within the sporangia, the spores of Actinostachys are bilateral (monolete), which means that there is a single line on the spore indicating the axis on which the mother spore was split into four along a vertical axis. The spores are smooth, with parallel indentations along them (Wheeler, 1998; Raven, Evert, & Eichhorn, 2005; Tindale, 1999; DPAW, 2014).
Actinostachys can be identified from their relatives the Schizaea by the flabelliform (leaf-shaped) frond blades (eol, 2014). The Actinostachys digitata is the only species native to Western Australia (DPAW, 2014).
Actinostachys was originally included within the genus Schizaea, however, it became segregated due to the flabelliform frond blade (eol, 2014). Little too no other information is available on the evolution of the Actinostachys, possibly due to its relatively recent segregation from Schizaea.
Kingdom – Plantae
Phylum - Charophyta
Class - Equisetopsida
Order - Schizaeales
Family - Schizaeaceae
Genus – Actinostachys
(ALA, 2014)
Actinostachys is a genus comprised of thirteen individual species distributed throughout tropical and subtropical regions, one species, the Actinostachys digitata, is endemic to Western Australia (DPAW, 2014). The Actinostachys digitata is located in the Northern Kimberly region of WA, as well as other areas in Australia, such as the Northern Territory and the Queensland Ranges, it is also present in Sri Lanka and throughout south east Asia (DPAW, 2014; Wheeler, 1998).
Image courtesy of Flora Base (FloraBase, 2014).
Actinostachys tends to grow in rainforest or forest margins, around the base of trees or palms, in sandy soil along creeks and among rocks in gullies (DPAW, 2014; Chinnock, n.d.; Wheeler, 1998).
This genus, and the species associated are not reported to have any significant relevance in connection with medicinal, consumable or ornamental uses.
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