244 GRASSES OF BRITAIN. 



AiRA CANESCENS. 



Clubbed Hair-Grass. 



Plate ex. 



Specific Characters. — Awns clavate, fringed in the centre. 



Description. — Root annual or biennial, fibrous, producing stems 

 from six to fourteen inches in length. Stems erect, round, smooth, 

 hollow, bearing four or five leaves with rough, striated sheaths ; the 

 upper leaf shorter than its sheath. Ligule of upper sheath promi- 

 nent, acute, about twice as long as broad. Joints about three, the 

 upper usually naked. Leaves setaceous, short, rough, and glaucous. 

 Infiorescence compound panicled, spreading while in flower, otherwise 

 close, frequently tinged with purple; the branches rough; the rachis 

 mostly smooth. Spikelets composed of two glumes and two florets. 

 Glumes of about equal lengths, membranous, acute, without lateral 

 ribs, minutely toothed on their keels. Florets shorter than the glumes, 

 of two paleae ; the outer palea acute, not beaked or bifid at the sum- 

 mit, without lateral ribs, hairy at the base, furnished with a long 

 dorsal awn ; the inner palea membranous, narrow, notched at the 

 summit, smooth on the lateral folds, and about the length of the outer 

 palea. Aivn arising from a little above the base of the outer palea, 

 and extending half its length beyond the palea, club-shaped above, 

 and furnished in the centre with a circular fringe. Styles two, short. 

 Stigmas long and feathery. Filaments three, slender. Anthers 

 short, dark purple. 



Obs. — Aira canescens is readily distinguished from all the other 

 British grasses in the form of the aims of the florets, which are club- 

 shaped and fringed in the centre, (see Fig. 3, magnified.) 



This is one of our rarest British grasses, found only on the sandy 

 coasts of Dorset, Norfolk, and Suffolk. It is of more frequent oc- 



Aira canescens, Linn., Eng. Bot., Knapp) Schracl., Smith, Hooker. Corynephorus car 

 nescens, Beauv., Koch, Kunth, Bab. 



