Description: Rhizome erect or creeping, bearing scales.
Fronds 1-pinnatifid to 1-pinnate (rarely simple or 2-pinnatifid); fertile and sterile fronds often markedly different.
Sori elongate, long or short, parallel with the midvein or the primary veins of the lamina, often becoming confluent with age, the indusium opening towards the vein.
Distribution and occurrence: World: 7 genera, c. 220 species, tropical to cool-temp. regions. Australia: 3 genera, c. 28 species, all States.
The morphologically distinct genus Doodia is nested within Blechnum, and closely related to Blechnum species such as B. cartilagineum (Shepard et al. 2007; Perrie et al. 2014; Gasper et al. 2016). This is problematic for classifications that reflect relationships because it means Blechnum in the traditional sense is not a natural group. Further, two species, Blechnum indicum and Blechnum serrulatum are not closely related to other Blechnum species. Perrie et al. (2014) transferred these two species to a new genus Telmatoblechnum. Two competing approaches to resolving the issues introduced by Doodia are currently available. In the first, Doodia is sunk, combined with Blechnum resulting in one large genus. In the other Doodia is retained, but to achieve that retention Blechnum is split into 15 genera (Gasper et al. 2016). We prefer to retain as far as possible the genus Blechnum as it is currently used, and for this reason we accept a single, broadly circumscribed genus that includes Doodia, but excludes the two Telmatoblechnum species. This approach involves the fewest changes to species names. We see this as preferable to introducing a generic classification comprising many small segregates, each with a new name. That picture of relationships resulting from recent molecular phylogenetic investigations can be just as well formalised using infrageneric ranks within Blechnum.
Text by Peter G. Wilson & Matt A.M. Renner
Taxa not yet included in identification key
| ||Key to the genera|| |
|1||Sori elongated, long, one on each side of the main vein and extending the full length of the segment, often covering the entire lower surface of the narrow segments of the fertile fronds in species with dimorphic fronds; veins of sterile fronds free||Blechnum|
|Sori short, initially discrete, usually in two rows on each side of the midvein, sometimes becoming confluent with age and covering the lower surface of the segment; veins of fertile and sterile fronds anastomosing, rarely free in the latter||Doodia|