Some key terms and features to look for when identifying ferns

Pinnae (singular: pinna): Stem scales: thin, papery the first level of division scales attached to the stem. on a fern frond. These may be on the stipe Pinnule: the second level only or may extend up the of division on a fern frond. rachis. They are often rusty Pinnulet: the third level in colour. of division on a fern frond.

Rachis: the term for the frond stem above where the leafy part of Sori (singular: sorus): the the frond begins. term for groups of sporangia. Sporangia (singular: Stipe: the term for the sporangium): individual frond stem below where spore-producing cases, often the leafy part of the found on the undersides of fronds. frond begins.

Rhizome: the stem of a fern which either grows Indusia (singular: indusium): underground or at the a membranous layer that covers soil’s surface. They can the sori while the spores are be upright or grow maturing. This layer will often horizontally as a shed when spores are mature ‘creeping’ rhizome. and ready to release. Rhizome

We are Plantlife For 30 years, Plantlife has had a single ideal – to save and celebrate wild flowers, plants and fungi. They are the life support for all our wildlife HRH The Prince Of Wales is our Patron and their colour and character light up our Plantlife landscapes. But without our help, this priceless Brewery House, 36 Milford Street, Salisbury, Wiltshire SP1 2AP natural heritage is in danger of being lost. 01722 342730 This guide to Ferns of Atlantic woodland was [email protected] created as part of the Building Resilience in South West Woodlands partnership project. www.plantlife.org.uk Plantlife is a charitable company limited by guarantee, Where wild flowers lead... company no.3166339. Registered in England and Wales, charity no.1059559. Registered in Scotland, charity no. SCO38951. Wildlife follows ©Plantlife, June 2020 ISBN: 978-1-913283-01-8 Photographs ©Roger Golding, Dr Alison Smith and Rachel Jones Designed and illustrated by evansgraphic.co.uk Ferns of Atlantic Printed by Blackmore, Shaftesbury, Dorset woodland This guide covers 14 of the common fern species Undivided Ferns with undivided fronds you are most likely to encounter in Atlantic Identifying ferns woodland (or temperate rainforest) habitat, The leafy part of a fern Hart’s-tongue fern Asplenium scolopendrium as well as two of the rarer species which are and its stem is known indicators of very healthy Atlantic woodland. For as a frond.  Evergreen fronds glossy, narrow and strap-like, with a information on the 60 or so species of UK fern, we The frond may be entire heart-shaped base and pointed tip. Often becoming have suggested guides below. (as one leaf) or it may Pinnate: divided once undulate (wavy) at edge. Medium-sized fern with fronds be divided into smaller to around 60cm. What are ferns? segments called pinnae.  Plants dark green and larger in shady conditions, pale green-yellow and stunted when exposed. Ferns appeared early in evolutionary history and have To begin with, it is useful  Sori arranged in horizontal lines either side of the stem a primitive method of reproduction involving producing to look at the number of on frond underside. Early in the year these lines appear spores. They were among the first plants to develop a times the frond is divided Bipinnate: divided twice pale but later turn rusty brown. vascular system, including roots, xylem and phloem from the main stem. The name scolopendrium, from the Latin for centipede, is vessels, to transport water and nutrients. This large Ferns in this guide are due to the appearance of the underside where the linear evolutionary step forward from their predecessors grouped into those with sori look like the many legs of a centipede. This species the bryophytes (mosses and liverworts), which lack a fronds that are undivided, only ever grows where lime is found in the soil. vascular system and absorb water through their surface, pinnate (divided once), enabled them to grow much larger. Ferns have two bipinnate (divided twice) distinct parts to their life-cycle known as alternation of Tripinnate: divided and tripinnate (divided three times generations. The large, familiar plant we call a fern is a three times). Sori in lines spore-producing sporophyte. When these spores land in a suitable place to grow, they form gametophytes – tiny green heart-shaped growths (or prothalli) Ferns with pinnate fronds (divided once from main stem) that produce sexual cells. When male cells fertilise female cells, another sporophyte begins to grow. Hard fern Blechnum spicant The way a fern grows is a useful identification What are Atlantic woodlands and feature. Many ferns have Common in acidic woodland why do ferns thrive there? a short vertical stem with  Evergreen fronds dark green, long and narrow, tapering Atlantic woodlands are a type of ancient semi- all the fronds arising gradually at the base and tip. Divided once into finger- natural, broad-leaved woodland. Often dominated from a central point, like leaf segments (known as ‘pinnae’), resembling ribs Shuttlecock by oak woods, they also include a mix of other tree giving a ‘shuttlecock’ or a ladder. Rather glossy and rigid. Medium-sized fern species, such as birch, alder, ash and hazel. Upland growth form. Some grow with fronds to around 40cm.  ‘Sterile’ fronds visible all year, and grow from a central ash woods and Atlantic hazel woods are some of as an open rosette, while Sterile frond the most important Atlantic woodland habitats. others have a creeping, point in a rather lax rosette. In summer, ‘fertile’ fronds horizontal rhizome with rise vertically from the centre. The pinnae are narrower Atlantic woodlands are found in western Ireland and from fronds appearing to arise and more widely spaced, and the backs are covered in the west coast of Scotland, through the Lake District and rusty-coloured sori. Wales to south-west England, where the climate is mild individually from the surface they are growing on. Open rosette This fern has a strong dislike of lime in the soil and is and wet with little seasonal change due to the Gulf Stream. therefore a very good indicator of acidic conditions. This wet and humid climate allows ferns to survive without The presence of two different types of frond on the needing to access moisture deep in the soil. As well as same plant in summer is highly characteristic. growing on the forest floor, here ferns are able to grow as Other terminology and ID epiphytes on trees, rotting stumps, rocks and banks. The features described in this Fertile frond rarer filmy ferns, which are only found in the far west of guide are explained in the Britain, have very thin, translucent leaves. Vulnerable to glossary on the back page. Polypody Polypodium species drying out, they can only survive in very wet places. Creeping rhizome Common growing as an epiphyte on trees, banks and walls in damp places Further information  Evergreen fronds are not glossy and are broad at the base and middle, narrowing towards the tip. The lower Books Websites pinnae are often folded inwards towards the middle of Key to Common Ferns (2005), Merryweather, J., Field www.ebps.org.uk The British Pteridological Society the frond. Small to medium-sized ferns with fronds Studies Council. website provides a wide range of information about ferns 10-40cm long. Ferns, Clubmosses, Quillworts and Horsetails of Cornwall including identification, courses, publications and a  Round sori can be found on the back of the frond and and the Isles of Scilly (2012), Murphy, R.J., Page, C.N., comprehensive glossary. vary from yellow to orange. Parslow, R.E. and Bennallick, I.J., Environmental Records http://data.nbn.org.uk The NBN Gateway hosts an There are three very similar species of polypody: Centre for Cornwall and the Isles of Scilly. up-to-date database of British fern distribution. common, western and southern but they are difficult to separate. All can be found in the south-west and can also Britain’s Ferns, Clubmosses, Spikemosses, Quillworts http://rogergolding.co.uk/ferns hybridise. The name polypodium comes from the Greek and Horsetails (2020), Merryweather, J., Princeton Many of the images in this guide are taken from Roger poly (many) and pous (foot) referring to University Press. Golding’s website ‘Ferns in Britain and Ireland; A guide the branching nature of the rhizome. to ferns, horsetails, clubmosses and quillworts’. Underside of frond

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Ferns with bipinnate fronds (divided twice from main stem) Male-fern Dryopteris filix-mas Scaly male-fern Dryopteris affinis agg

 A large deciduous fern with fronds to 100cm or more in Common in acidic woodlands with high rainfall length. Frond is broadest in the middle and narrower at base and tip.  A large deciduous or semi-evergreen fern with fronds  Pinnules taper to a pointed tip and the pinnule edges to around 150cm. Frond is broadest in the middle and have rounded teeth. narrower at base and tip.  Stem scales are more sparse than in the scaly male-  Pinnules parallel-sided to tapering, with square to ferns, and do not extend all the way up the rachis. rounded tips. Teeth on margins prominent to absent. One of our most common ferns, it can be separated from  Stem scales are dense and golden to rusty-coloured. scaly male-fern (right) by looking at the underside of the These extend all the way up the rachis (but note that frond where the pinnae join the main stem. This junction scales rub off and may be sparse later in the season). is green in male-fern but black in scaly male-fern.  All the scaly-male ferns have a dark spot where the pinna joins the rachis on the front of the frond (may need to scrape away scales to see this). This helps separate scaly male-ferns from male-fern. There are several different forms of scaly male-fern that have recently been classed as separate species, but they are rather difficult to tell apart.

Soft shield-fern Polystichum setiferum Hard shield-fern Polystichum aculeatum

Very common in south-west woodland Less common than soft shield-fern, tends to be found where there are pockets of limestone  A large semi-evergreen fern with fronds to around 120cm. Pinnae towards the base of the frond are  A medium to large evergreen fern with fronds to similar in length to those in the middle of the frond around 90cm. Pinnae towards the base of the frond (contrast with hard shield-fern). are shorter than those in the middle of the frond  ‘Mitten’-shaped pinnules have a small distinct stalk (contrast with soft shield-fern). with none of the leafy part of the pinnule reaching the  ‘Mitten’-shaped pinnules have an indistinct stalk with midrib. Angle of base of pinnule more than 90 degrees. the leafy part of the pinnule reaching the midrib. Mittens  The ‘thumb’ segment of the mitten tilts to the pinna Angle of base of pinnule less than 90 degrees. midrib (contrast with hard shield-fern).  The ‘thumb’ segment of the mitten tilts away from This fern dislikes stagnant wet conditions and tends to pinna midrib (contrast with soft shield-fern). Angle more grow on damp but well-drained soils, often preferring Angle less The dark green fronds of this fern can appear more than 90 than 90 degrees slopes, banks and the edges of ditches where water degrees glossy and leathery than soft shield-fern. It often grows drains away freely. in rocky places such as stony banks, rocky stream banks, gorges and cliffs.

Lady-fern Dryopteris filix-femina Filmy ferns Hymenophyllum species

Wilson’s filmy fern Tunbridge filmy fern Widespread and common, particularly around Common in acidic woodlands with high rainfall stream banks  Small, delicate evergreen ferns that have translucent  A medium to large deciduous fern with fronds up to leaves with prominent dark midribs. Fronds typically 150cm. Stem may be green or red. 2-10cm long.  Pinnules are finely toothed but not mitten-shaped like  Spore-producing cases are enclosed in circular the shield ferns. These finely lobed pinnules give the fern indusia, the edges of which are ragged in Tunbridge a feathery appearance, and can make it look as though it filmy fern but smooth in Wilson’s filmy fern. is tripinnate. These delicate and uncommon plants are unlike any of  The sori are ‘sausage’-shaped or ‘J’-shaped in contrast to our other ferns and can easily be overlooked as mosses the more rounded or kidney-shaped sori on the shield- or liverworts growing low down on tree trunks or rocks. ferns and male-ferns. They’re usually found in very humid spots beside A beautiful fern whose fronds are very sensitive to frost, waterfalls, along rocky river edges or in gorges. often turning yellow or brown with the first frost of the year.

J-shaped sori Ferns with tripinnate fronds (divided three times from main stem) Broad buckler-fern Dryopteris dilatata In addition to the woodland ferns, look out for these species which are common on walls, rocky banks and rock outcrops Very common woodland species  A medium to large fern with broad to triangular deciduous fronds, up to 120cm. Maidenhair spleenwort Rustyback  Lower pinnae have a triangular outline. Pinnule edges Asplenium trichomanes Asplenium ceterach tend to curve downwards (see left).  Stem scales from the base of mature fronds have a dark stripe or broad dark patch in the middle. It can help to remove a scale and hold it up to the light to check this. The similar narrow buckler-fern lacks this feature and does not have the shuttlecock growth habit. One of our commonest ferns, this species dislikes lime and grows predominantly in acidic habitats, especially damp, sheltered woodland.

Pinnule edges Hay-scented buckler-fern Dryopteris aemula

Common in acidic woodlands with high rainfall Very common and widespread Common on old walls and  Similar frond shape to broad buckler-fern, but the evergreen fronds are smaller, typically up to 60cm long.  A small evergreen fern with thin, dark brown to limestone outcrops  Pinnule edges curve upwards rather than being flat black frond-stems, and short, roundish pinnae.  A small, evergreen fern with pinnate fronds, the or curving down, and they have a crinkled or crimped Older fronds often shed their leaflets, leaving rounded pinnae forming a ‘zig-zag’ pattern. appearance (see left). the bare stems that resemble black hairs  The backs of young fronds are densely clothed  Stem scales do not have a dark vertical patch or stripe (trichos is Greek for hair). in pale brown scales that turn a deep rust colour like broad buckler-fern. Instead they have a dark with age, hence the common name. horizontal stripe at the scale base (though this can be tricky to see – the scale needs to be removed in its entirety and held up to the light). Wall-rue Black spleenwort A beautiful fern with distinctive bright green fronds, it can Asplenium ruta-muraria Asplenium adiantum-nigrum be distinguished from broad buckler-fern by the dense covering of glandular hairs on the underside of the fronds, easily seen with a x10 lens. These glands release a sweet scent when rubbed, hence the common name.

Pinnule edges Bracken Pteridium aquilinum

Very common in south-west woodland  Large deciduous fern varying from 50cm to over 200cm tall, often covering large areas.  Pinnae are large and stalked, giving a branched appearance.  Sori, when present, are found on the underside, along the leaf margins. One of our commonest and most abundant ferns, its size and highly branched fronds make it easy to identify. Common on mortared walls and Common on mortared walls and not too Large stands of bracken can develop on open hills, acidic stony banks and rocks moorland and heathland, covering many acres of land. It lime-rich stone is generally less vigorous in woodland but can still form  A small evergreen fern with bipinnate fronds  A small evergreen fern with rather shiny, dense patches in some places. and fan-shaped pinnules on green stalks. triangular, tripinnate fronds. The frond stems are dark brown to black towards the base.