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A useful way of identifying ferns can be to look at pictures and it doesn’t take long just to flick through the pages of Streeter (2009) to find Maidenhair Spleenwort A trichomanes but it looks very  similar  to A viride. By reading the descriptions of each plant it is possible to accurately identify the species. .( A viride has a green not dark stipe and rachis.)

The other alternative is to use a key to identify the plant looking at particular characteristics such as size, leaf shape, sori shape etc. This means taking a very close look at the plant using a hand lens and then answering various questions about its  diagnostic features until hopefully the correct conclusion is reached. In Streeter (2009)on page 32 there is a separate key for Aplenium Spleenworts which shows how this works. (1- Pinnate means 2 rows of leaflet along a single axis)

1. leaves irregularly and sparsely forked into narrow linear segments

A septentrionale

Leaves 1 – 3 pinnate, lobes not linear                                             2

2. Leaves pinnate                                                                          3

leaves 2-3 pinnate                                                                         5

3. Upper part of rachis with green wing, leaf thick and glossy, pinnae

less then or equal to 15mm ( sea cliffs, caves)

A marinum

Rachis not winged, pinnae less than 12mm                                       4

4. Rachis black                                                        A trichomanes

IMG_5905

This is a tracing of an individual leaf blade of A trichomanes. The central stalk is called a stipe near the base where there are no leaves. Where there are leaves the central stalk is called a rachis. Either side of the rachis small leaflets are connected called pinnae. I sketched an enlarged illustration of an individual pinna showing how it is attached to the rachis with a very small stalk. The outline is not straight but slightly wavy. As this is the underside of the pinna it is possible to determine the shape of the 5 sori which are very pale, could they be next year’s fertile sporangia? At 8cm long and with pinnae of about 4mm this plant is well described in Streeter (2009).

IMG_5900

This is the same leaf blade I traced, viewed from underneath,  showing the dark stipe and rachis as well as the pale sori shapes on the individual pinna.

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