West Highland Flora

Hard Shield Fern


Polystichum aculeatum

 

Polystichum aculeatum

Photo Carl Farmer
22 Sep 2001 Storr, Skye

Frequent in rocky places, especially on limestone.

Fronds vary greatly in length, from c 15-100 cm

ID: Pinnlues with sharply pointed teeth and spine-pointed tip.  Lowest pinnae much shorter than middle ones.  Leaves stiff.  Pinnules mostly unstalked or with short "stalk" which is simply a narrowing of the pinnule.  Basal sides of all pinnules form an angle less than 90 (see pic below right), except sometimes for pinnules close to the rachis.  In Soft Shield Fern, this angle is 90 or more on most of the pinnules.  Hybrids between the two have been recorded.

Other features: Much more shiny in appearance than most ferns, having a very sleek and classy look.  Very small specimens are found with all the pinnae merely lobed instead of divided into pinnules, but there are usually better-developed specimens nearby.  If not, Holly Fern is a possibility, see that species for differences.

Common on limestone where fronds exposed to the light are usually pale green but those in shady crevices are darker green.  Also found on non-limestone rocks, generally with deep green fronds in damp shady gorges or beneath rock overhangs.

 

Polystichum aculeatum

Photo Carl Farmer
11 Aug 2003 Torrin, Skye

  Polystichum aculeatum

Angle at base of pinnule.

Compare picture on
Soft Shield Fern
page

 

 

Polystichum aculeatum

Photo Carl Farmer
25 Apr 2004 Portree, Skye

Overwintering fronds


Back to species list