Printed
Colour Identification Guide to the Grasses, Sedges, Rushes and Ferns of the British Isles and North Western Europe by Francis Rose (Viking, 1989. 240 pages). Definitive and authoritative guide to over 400 species, over 350 illustrated in colour. Technical key. Expensive.
Collins Wild Flower Guide. The most complete guide to the Wildflowers of Britain and Ireland by David Streeter and others (Collins, 2nd edition 2016). This has a substantial section on grasses and sedges with colour illustrations and keys to each section, plus up-to-date botanical names. Not a pocket guide, quite a brick, but good for cross-reference.
Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland by Roger Phillips & Sheila Grant (Pan/Macmillan 1980) High quality photos. Available second-hand.
A Field Guide to Grasses, Sedges and Rushes by Dominic Price (The Species Recovery Trust, undated ?2016) Covers only 100 species. Colour photos. Has guides by habitat. A3 ring-bound.
Start to Identify Sedges and Rushes by Faith Anstey (2019) 36 page booklet with colour photos.
Grasses
Common Grasses by Mark Gardener & Carol Roberts (Field Studies Council, Wild ID fold-out card, 2022).
Colour illustrations of 30 common British grasses, with a lateral key to enable rapid comparison of seven features of grasses.
Grasses. A guide to their structure, identification, uses and distribution in the British Isles by Charles E Hubbard (Pelican, 1954: 3rd edition 1984. 476 pages).
Continuously in print for almost 70 years: many available second-hand. Two pages to each species, one with line-drawings showing detailed features as well as the entire plant. Identification key. Later editions have more up-to-date species names and revisions to text.
Grasses of the British Isles (BSBI Handbook No. 13, 2009. 612 pages) by Tom Cope & Alan Gray. Text and line drawings of each species. Key to Tribes, Genera & Species.
Grasses: a guide to identification using vegetative characters by Hilary Wallace (Field Studies Council, AIDGAP guide, 2021, 108 pages) Dichotomous key. Colour photographs
A Field Key to the Grasses of the East Midlands by Brian N K Davis. (Huntingdonshire Fauna and Flora Society 2008, 2nd ed 2009). Covers 105 lowland species, including 30 common species shown in bold. A4 format with b&w photo-scans of pressed specimens.
Free to download: http://hffs.genesis-ws.co.uk/index.php/publications/grasses-of-the-east-midlands
Grass ID sheets online. On the BSBI’s Plant Crib page you’ll find ID sheets for many grass species and genera, from Arrhenatherum (false oat-grass) and Bromus (bromes) to Spartina (cord-grasses) and Trisetum flavescens (yellow oat-grass).
Ken Adams has a series of ID keys to groups of grasses such as fescues, meadow-grasses and bents (Agrostis spp.) and a page showing the structure of grasses: Index page to his Keys.
Sedges
Sedges of the British Isles by A C Jermy, D A Simpson, M J Y Foley, M S Porter. (BSBI Handbook No. 1. Edition 3, 2007. 554 pages). For each of the 106 species: text, line-drawings, distribution map. A comprehensive handbook covering sedges and their hybrids: all 76 species of Carex as well as all 30 of the other genera in the Cyperaceae, including: Cotton-grass (Eriophorum), Deer-grass (Trichophorum), Club-rush (Scirpus, Schoenoplectus, Scirpoides, Isolepis), Spike-rush (Eleocharis), Galingale (Cyperus), Flat-sedge (Blysmus), Bog-rush (Schoenus), Fen-sedge (Cladium), Beak-sedge (Rhynchospora), and False-sedge (Kobresia).
Collins Pocket Guide: ‘Grasses, Sedges, Rushes & Ferns of Britain & Northern Europe’ by Richard Fitter, Alastair Fitter & Ann Farrer (Collins, 1984. Reprinted many times).
Has colour illustrations with line drawings of detail, but I find the colour pages rather crowded. It has what it calls a Single-access key by which you check against a list of characters to narrow down your search. Plenty of copies available second-hand, ranging from £6 to £107.
Rushes
Rushes by Wallace, Roberts & Lawrence (Field Studies Council, Wild ID fold-out card, 2018). Colour illustrations of 32 rushes (Juncus) and wood-rushes (Luzula) with a lateral key for each of these. Colour illustrations with magnified views of key diagnostic features: flower heads, stem pith and seed shape.
Websites
Google Lens: Go to google.com and there is a camera icon at the right of the search bar. Click on this, and you can drag and drop any image and it will do its best to identify it – so can be used for any flora and fauna, vertebrates and invertebrates etc. (as well as buildings, landscapes – anything, in fact.) Worth a look, but treat identifications with caution!
Apps