Identifying Grasses

Do you know your ligules from your glumes?  The Big Meadow Search – and there are still a couple of days left in July to search some more – has been a good reminder (to me at least) that identifying grasses is often not easy.  A few years ago, we arranged a course for CMG members on grass ID which was very helpful; but if you don’t regularly use the knowledge acquired on such courses it tends to fade.  Some species are relatively easy, but many are not, if you don’t know what to look for.  So, short of finding another course to go on (and many grasses have now finished flowering so you’d have to wait until next year) what can you do to get a bit more competent at identifying grasses?  Here are several suggestions, some of which Laura has already put up on the CMG Facebook page, but for those who don’t use Facebook they are included here as well.

A useful book with a self-explanatory title is “Start to Identify Grasses”, by Faith Anstey. It has just been re-issued in A5 format as opposed to the A6 of the original.  The new edition has some extra explanation and photos, and the bigger format makes it easier to see some of the detail in the diagrams.

This book is intended to ease the reader in gently, by avoiding highly technical keys, and only concentrating on the 20 most common species to be found in neutral (as opposed to calcareous or acid) lowland grassland.  If you become familiar with these 20, you will know when you’re seeing something else, and will need further keys or advice.  Like most ID guides, this one uses flower structure and characteristics a lot, so would be less helpful with grasses not in flower, or without old flower heads still attached.  The flowchart it uses to narrow down the options is much easier to use than many of the more advanced keys, but then it misses out a lot of grass species.

Another of the easy-to-use guides is this laminated fold-out one from the Field Studies Council (FSC):

As well as the useful large illustrations which include diagnostic features for species ID, it has a lateral key (as opposed to the usual dichotomous key) where you look along the rows of a table (one row to a species) to see how many of the listed characteristics match those of your specimen. This guide includes 30 species, commonly found in meadows, woodland and riverbanks, waste ground and roadside verges.

General wildflower field guides often don’t include grasses, but one that does is the Collins Wild Flower Guide, and it also has a key to aid identification of all the grasses native to the UK and Ireland.

To use the key, you need to know the terminology used.  Laura put a link to this video on our Facebook page:

This is the first of a planned series of videos, and is an excellent way of learning the necessary botanical terminology, even if you don’t have any botanical experience. It was produced as one of the National Plant Monitoring Scheme support resources.

Most ID guides and keys to grasses require examination of the flower heads, potentially limiting field surveys to only a few months of the year.  It is possible (but harder) to identify grasses when they aren’t in flower, using non-flower (vegetative) features.  This guide:

uses only vegetative characters to identify all the grass species found in the UK, and so can be used during much more of the year, outside of normal flowering times.  It is part of the FSC’s AIDGAP series (Aids to Identification in Difficult Groups of Animals and Plants).

Another useful video Laura has posted on the Facebook page is this “Introduction to Grass Identification:

It was produced by the Species Recovery Trust, and in the video, Dominic Price (who founded the SRT) shows us the diagnostic features of various commonly encountered grasses.  There is also a book by Dominic Price produced by the SRT: 

This guide includes some sedges and rushes as well as grasses.  There is no key as such, instead, unlike many other guides, this one breaks the species down into those likely to be found in various habitats, with lists for neutral (mesotrophic) grassland, heathland and dry acid grassland, calcareous/chalk grassland, wet heath and mire, woodland, and ponds, rivers and wetlands. Each species is then described in detail, with clear photos of its diagnostic features, and the habitats in which it occurs are given.

As with most things requiring knowledge and skill, the best way to become competent at identifying and recording grasses is to get on and do it, there’s no substitute for experience, but one or more of these guides should help to ease you into it and make it a bit less daunting.


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