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Notes - Carex aeutiformisl Grid square nomenclature 15Carex acutiformisEnwARD PRATT, 7 Bay Close, Swanage, Dorset, BH19 IREThe article on pages 344-5 of Plant Crib 1998 sheath. (However in one population perverselyis most helpful, but there is just one point which it is not clearly visible either above or below thedoes not seem to work, at least in this area. I ligule!)find that in Carex acutiformis the aerenchyma Reference:pattern is usually clearly visible just above the RICH, T.C.G. & JERMY, A.C. 1998. Plant Crib 1998.ligule, and from both inside and outside the BSBI, LondonGrid square nomenclatureMARK WILLIAMSON, Department of Biology, University of York, Y010 5DD; mw1@york.ac.ukTREVOR JAMES, clo Biological Records Centre, CEH MonIes Wood, Abbots Ripton, Huntingdon,PE28 2LSI; tjj@ceh.ac.ukDAVID PEARMAN,Algiers, Peoek, Truro, Cornwall, TR3 6RA; dpearman4@ao1.comBSBI members pioneered the use of ten kilometreby ten kilometre grid squares for recordingdistributions with the Old Atlas (perring &Walters 1962) where the bulk ofthe field recordswere made between 1954 and 1958. From 1956botanists conducting local surveys began usingtwo kilometre by two kilometre squares. Somehistory of that is in the New Atlas (preston et al.2002, p. 8). In the new Change atlas (Braithwaiteet al. 2006) these squares are called tetrads andeither 10-km squares or hectads. This note isabout the origin and validity of the -ad names.Tetrad has become a generally accepted term buthectad is still controversial.Tetrad is the easier of the two. It seems to havefirst been used by E.S. Edees in Staffordshire inabout 1956 (Preston et al. 2002) though his Florawas published much later (Edees 1972). The firstFlora with the word is by J.G. Dony (1967) andhe also invented the system of labelling the 25tetrads in a 10-km square with capital letters,sometimes called DINTY, around 1960 (pers.comm. to TJJ). Tetrad is a standard English wordmeaning a group of four or the number four(Oxford English Dictionary Onlinehttp//:dictionary. oed.com) and that dictionarygives the meaning here as f. Eeol., first publishedin Hawkes & Readett (1963). However, tetradalso appears in the dictionary entry '-ad, suffix!''forming ... Collective numerals, as ... monad, ...dyad, triad, tetrad, pentad, hebdomad, chiliad,myriad, etc.'The commonest objection to hectad is that it isan unfamiliar neologism while the commonestobjection to not using it is that 10-km square isinaccurate, the proper name should be somethinglike the phrase in our first line, e.g. Williamson(2002) 'hectads (lO-km x 1O-km grid squares)'.The Old Atlas (Perring & Walters 1962) calledthem 1O-kilometer grid squares or lO-kilometresquares while the New Atlas (Preston et al. 2002),after saying (p. 3) 'the 10 x 10 km squares of the(British) Ordnance Survey National Grid', refersto them in the text as lO-km squares but on themaps as 10 km 2 • Neither uses hectad. Hectadwas invented by the late Guy Messenger(Messenger 1987) 'The HECTAD is a lO kmsquare in any system in which the TETRAD is a2km square.' He justifies it by first pointing outthat in TETRAD 'both its syllables are soundlybased on good Greek' and that is indeed so forboth the dictionary entries mentioned above. Hethen argues 'when you multiply a unit by 100 yougive the unit name the prefix Hecto-' and so youdo, or Hect- in front of a vowel, but Hectodoesn'tlead to Hectad. That argument only leadsto hectad if you regard it as Hect- in front of -ad.Hectad is not in the Oxford English Dictionary(yet) but it could be argued that it is covered bythe etc. in the examples of -ad given above. Nodoubt both lO-km sq and hectad will continue incommon use whatever one may feel about themand some of us do have strong feelings.The list above of -ad words from a dictionarygives two other square measures that could be,and sometimes are, used: monad for 1km x lkmand myriad for 100km x 100km (one meaning ofmyriad is lO,OOO). Both seem a bit dubious inview of the other meanings of those words.Messenger (l987) suggested haplad for 1km xlkm but that would be cognate with tetraplad nottetrad; hapl- is single, mon- is one. The otherterms in the list above, for collections of two,three, five, seven and a thousand, are all fornon-square numbers and so cannot be used ingrid square mapping. It would seem that 5km x5km and 50km x 50km units would only havevery obscure Greek -ad terms.