164 GRASSES OF BRITAIN. 



DiGlTARIA HUMIFUSA. 



Glabrous Finger-Grass. 



Specific Characters, — Glumes equal. Sheaths smooth. 



Description. — Root annual, fibrous, producing several stems from 

 four to nine inches in length. Stems branched and decumbent at the 

 base, then ascending, smooth, striated, hollow, polished, bearing usually 

 four leaves with smooth striated sheaths, the upper sheath much longer 

 than its leaf. Ligule of upper sheath obtuse, occasionally furnished 

 with hairs at its base. Joiiits about three, situate near the base, and 

 mostly covered by the sheaths. Leaves short, flat, rather broad, not 

 hairy, the margins rough. Inflorescence digitate, the branches long 

 and linear, from two to four in number. Racliis flattish and somewhat 

 angular, with the marginsminutely toothed, bearing unilateral spikelets 

 arranged in pairs or threes on footstalks of unequal lengths. Spikelets 

 dorsally compressed of an oval form, composed of two glumes and one 

 floret. Glumes of equal size, pubescent, five-ribbed, the inner glume 

 of a deep purple, the outer but slightly tinged. Floret equal in length 

 to the glumes, of a deep reddish purple, of two nearly equal paleae, mi- 

 nutely striated and glossy, becoming of a horny texture as the seed 

 ripens ; inner palea folded and entire at the margins. Filaments three, 

 rather longer than the palese. Anthers short, violet-coloured, cloven 

 at each extremity. Styles two, slender, about the length of the stamens. 

 Stimgas purplish, short, feathery, dense. Seeds hard and polished. 



Obs. — Digitaria humifusa is distinguished from Digitaria san- 

 guinalis in the glumes being of equal size, and containing but one 

 floret, (see Fig. 2.); — while in Digitaria sanguinalis the glumes are 

 very unequal, and contain two florets. 



Digitaria humifusa is distinguished from Cynodon Dactylon in the 

 spikelets being dorsally compressed, and arranged on the rachis in 

 pairs or threes (see Fig. 1). Glumes oval. Ligule distinct, (Fig. 5.) ; 

 — whereas in Cynodon Dactylon the spikelets are laterally compressed, 



Biffitaria humifusa, Pers., Hook., Bab. Synthcrisma glabrum, Schrad. Panicum 

 fjiabrum, Koch. Panicum humifusum, Kunth. Digitaria filiformis, Koel. Pani- 

 cum sanrjuinale, Pollich. 



