Fern Allies & Unusual Ferns

Small Adder's-tongue Krauss's Clubmoss Pacific Mosquito-fern Krauss's Clubmoss



What are they?

This page includes a small assemblage of somewhat atypical fern species, together with other, non-flowering, vascular plants that also spread by means of spores rather than seeds.



Lesser Clubmoss Family - Selaginellaceae

Krauss's Clubmoss      Selaginella kraussiana

Introduced from tropical Africa. Long-established in the Abbey Gardens area, Tresco and first recorded outside the gardens in 20216.

Krauss's Clubmoss Krauss's Clubmoss Krauss's Clubmoss Krauss's Clubmoss
Habit
Habit
Leaves
Leaves


Horsetail Family - Equisetaceae

Field Horsetail      Equisetum arvense

Native in the UK but probably only an introduction on the islands and not seeming to persist. Cones on pale brownish, unbranched stems in April-May and withering as the green, branched stems emerge. Stems with 6-19 ridges and of two types - stands of straight, upright stems, or mats of curled or twisted stems, all growing from a far-reaching, deep-seated and persistent root stock.

Field Horsetail Field Horsetail Field Horsetail Field Horsetail
Prostrate stems
Upright stems
Upright stems
Upright stems
Field Horsetail Field Horsetail
Leaf sheaths and branches
Cones


Adder's-tongue Family - Ophioglossaceae

Common Adder's-tongue      Ophioglossum vulgatum

Native. Previously recorded from a single site on the north side of St Agnes. Spore-bearing fronds may be found from late May to August. The above-ground, visible part of this plant consists of an oval-shaped, sterile leaf, from the base of which appears the elongate spike that is the fertile leaf that bears the spores. Some shoots consist only of simple, sterile leaves and these are easily passed over and not readily recognised as being an adder's-tongue. Plants may grow to around 25cm in height when among taller vegetation, but are often much less, typically 5-10cm in height.

Common Adder's-tongue Common Adder's-tongue Common Adder's-tongue Common Adder's-tongue
Habit
Fronds
Fronds
Fertile frond


Small Adder's-tongue      Ophioglossum azoricum

Native. Single plants and small colonies appear sporadically on the main five inhabited islands in heathy, short-turf habitats and damp hollows. Spore-bearing fronds may be found from April to August.

Small Adder's-tongue Small Adder's-tongue Small Adder's-tongue Small Adder's-tongue
Emerging plants
Emerging plant
Fronds
Fertile frond
Small Adder's-tongue Small Adder's-tongue Small Adder's-tongue
Fronds
Fertile frond
Tall plants


Least Adder's-tongue      Ophioglossum lusitanicum

Native. Extremely rare, with the only colony in the British Isles occurring towards the southern end of St Agnes in short turf. Plants are tiny, typically just 2-2.5cm in height. Leaves narrower than those of other adder's-tongues and often slightly keeled. Spore-bearing frons ripen typically during January-March, though young fertile fronds begin to emerge in October.

Least Adder's-tongue Least Adder's-tongue Least Adder's-tongue Least Adder's-tongue
Habit
Fronds
Fronds
Sterile frond


Moonwort      Botrychium lunaria

Native. A rare plant of coastal dune grassland. Formerly recorded from Bar Point, St Mary's and more recently from the south end of Tresco. Spore-bearing fronds typically found from June to August. A more elaborate plant than the adder's-tongues, with a strongly lobed sterile leaf and a branched, fertile leaf which carries the spores in small, grape-like structures.

Moonwort Moonwort Moonwort Moonwort
Habit
Fronds
Fronds
Fertile frond