370 HORTUS GRAMINEUS WOBURNENSIS. 



proportion of saccharine matter Ib afforded by the culms of this 

 grass than by the leaves. 



Flowers about the third week in July. 



ELYMUS geniculatus. Knee-jointed Lyme-grass. 



Specific character: Spike bent perpendicularly downwards, 

 loose ; calyx bristle-shaped, spreading, longer than the spike- 

 lets; leaves sharp-pointed. 



Obs. — A singular habit of this grass is, that the spike, just be- 

 fore flowering, bends down by the assistance of a joint near 

 the foot of the spike-stalk. Engl. Bot. 1586. Hort. Gram. 

 Fol. 268. 



Native of Britain. Root perennial. 



Experiments. — At the time of flowering, the produce from a 



sandy loam is — 



Produce per Acre. 



dr. qr. lbs. 



Gfass, 30 oz. The produce per acre - 20418 12 



80 dr. of grass weigh, when dry - 32 > 8167 8 



The produce of the space, ditto - 192 3 



The weight lost by the produce of one acre in drying 12251 4 



64 dr. of grass afford of nutritive matter 3 17 -.Qog ^^ j 

 The produce of the space, ditto - 24 0^ 3 



Tlie root is powerfully creeping, and the foliage is tough and 

 coarse. The quantity of nutritive matter it affords is not con- 

 siderable. It seems, therefore, to be but little adapted for useful 

 purposes. Sir J. E. Smith, in the EngUsh Botany, informs 

 us, that it was discovered in the salt marshes of Gravesend by 

 Mr. Dickson, and that Mr. Curtis was the first to distinguish it 

 from the Eli^mus arenarius, — as it seems even Linnaeus had con- 

 founded them. 



The Elymus arenarius is nearly allied to this species in its 

 general habit, but differs specifically in the spikelets being pubes- 

 cent, more compact, and the spike perfectly upright. The leaves 

 are broader, culms taller and stronger, and the root is more 

 powerfully creeping. The pubescence on the spikelets, and the 

 close order in which they are placed on the spike-stalk, with the 

 upright habit of the spike before and after flowering, seem to be 

 good specific distinctions — with the exception of the last; as the 

 first two indicate an excess of saccharine matter in proportion to 



