GRASSES OF IOWA. 



37 



DESCRIPTION. 



Johnson Grass. A stout perennial, with smooth, erect, simple 

 culms, 3 to 5 feet (7-13 dm.) high, and strong creeping root- 

 "stocks. Leaves elongated, one-fourth to three-fourths inches wide, 

 acute; ligule ciliate, and on the hack where the leaf-blade joins the 

 sheath there is more or 

 less pubescence. Panicle 

 open, 6 to 12 inches 



(12-25 cm -) l' on g> tne 



whorl'ed branches naked 

 below, the three to five 

 flowered racemes clustered 

 towards their extremities. 

 Pedicels of the staminate 

 (rarely neutral) spikelets 

 pilose with stout hairs. 

 Sessile spikelet broadly 

 lanceolate, acute 2 to 3 

 lines (4-6 mm.) long, pale 

 green or violet, becoming 

 dark or nearly black at 

 maturity. Callus small, 

 obtuse, shortly and sparse- 

 ly barbate. First glume 

 coriaceous, sparingly pub- g(. jl 

 escent on the flattened ^ 

 back, 5 to 7-nerved ; sec- 

 ond glume similar and 

 equalling the first, convex 

 below, subcarinate above, 

 acute, the hyaline inflexed 

 margins ciliate; third 

 glume a little shorter than 

 the outer ones, membra- 

 nous, faintly two-nerved 

 the infolded margins ciliate ; fourth glume broadly oval, obtuse, 

 nearly one-hali shorter than the second, two-lobed or bidentate at 

 the apex, ciliate, awned. Awn 5 to 8 lines (10-16 mm.) long. Palea 

 a little shorter than its glumes, nerveless, ciliate. Introduced and cul- 

 tivated in man_\- of the southern states for hay. In many places it has 

 become a dangerous weed, difficult to exterminate. 



Fig. 25. Andropogon Halepensis Brot. For detail 

 description, see fig. 20. (Div. of Agros. U. S. Dept. 

 Agrl. ) 



