This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
[Tragus Hall. Hist. Stirp. Helv. 2: 203. 1768. Lappago Schreb. Gen. 55. 1789.] Annual grasses, diffusely branched, with flat leaves and 1-flowered deciduous spikelets, either solitary or in clusters of 3-5 in a terminal spike. Scales of spikelet 2 or 3, the outermost small or wanting, the second rigid and covered with hooked prickles, the third membranous, subtending a palet and perfect flower.
Species 2 or 3, in tropical and temperate regions. Type species: Cenchrus racemosus L.
Cenchrus racemosus L. Sp. PI. 1049. 1753. Lappago racemosa Willd. Sp. PI. 1: 484. 1798. Nazia racemosa Kuntze, Rev. Gen. PI. 780. 1891.
Culms 2'-l4' tall, erect, simple to diffusely branched, smooth below, pubescent above. Sheaths smooth and glabrous; leaves l' - 3' long, 1 "-2" wide, acuminate, rather strongly ciliate; spike 1'-4' long, sometimes partially included in the somewhat inflated upper sheath; spikelets 1-flowered; first scale very small, almost hyaline; second scale coriaceous, 1 1/2" long, acute, 5-nerved, each nerve armed with a row of hooked prickles; third scale 1" long, keeled, sharp-pointed 1-nerved, membranous, enclosing a palet of like texture and a perfect flower.
Occasional in ballast and waste places about the Atlantic seaports. Native of Europe and Asia. July-Sept. Burdock-grass.