The involucral spikelets are male or neuter, the largest, and consist of three glumes. The first glume is oblong, lanceolate, dorsally flattened, many-nerved, margins narrowly incurved and keels narrowly winged. The second glume is membranous, lanceolate, acute, 3-nerved, with ciliate margins. The third glume is hyaline, smaller than the second, 1-nerved or this glume may be absent, stamens have large anthers. The pedicelled spikelets are similar to the involucral in every respect but smaller, male or neuter, but the first glume is not winged on the keels. The bisexual (or female) spikelets are smaller than the involucrant spikelets, linear-oblong, subterete, obtuse with a rigidly bearded callus. There are four glumes in the spikelet. The first glume is terete, or dorsally compressed or channelled, coriaceous and at length hardened, margins incurved, dark brown to almost black when old. The second glume is as long as the first, linear, dorsally chartaceous, with broadly incurved membranous margins, 3-nerved. The third glume is very small, hyaline, 1-nerved, epaleate. The fourth glume is the flattened base of the awn, epaleate. The lodicules are two, cuneate. Anthers are rather small. Styles are laterally or terminally exserted. Grain is narrow, obovoid, biconvex, with two grooves on the anterior side and with a long embryo. =Anthistiria tremula, _Nees_=. This is an annual or perennial. Stems are stout or slender, erect or ascending from a creeping root-stock, simple or branched, 1 to 4 feet. The _leaf-sheath_ is smooth, compressed. The _ligule_ is a narrow membrane. The _leaf-blade_ is linear-lanceolate, rigid, erect, acuminate with a setaceous tip, nearly smooth, varying in length from 6 to 20 inches and in breadth from 1/6 to 2/3 inch. The _inflorescence_ is an elongate panicle, 1 to 2 feet long, consisting of rather distant fascicles of spikes and bracts on capillary, flexuous peduncles; the spikes are sub-flabelliform or sub-globose, 1/2 to 1-1/2 inches broad, sometimes reduced to a few spikelets and bracts; the outer bracts are longer than the fascicles, 1 to 1-1/2 inches long, glabrous or hairy with ordinary or tubercle-based hairs; proper bracts are lanceolate, acute, compressed, glabrous or hairy with membranous margins. [Illustration: Fig. 165.--Anthistiria tremula. 1. Fascicles of three spikes with the outer bracts and proper bracts; 2. a spike without its proper bract; 3. the pedicelled and the bisexual spikelets without the involucral spikelets; 4, the first glume of the involucral spikelet with one wing only; 4a. the first glume of the involucral spikelet with wings to both the keels; 5 and 6. the second and the third glume of the involucral spikelet; 7, 8 and 9. the glumes of the bisexual spikelet; 10, 11, 12 and 13. glumes of the bisexual spikelet; 14. ovary.]