p.5

733
EXPLANATION OF THE PLATES.

MELICA.- A magnified spikelet of M. mutica, expanded, showing the glumes, two perfect flowers, and an abortive one.
GYCERIA.- A magnified spikelet of G. nervata (1); a separate flower with one joint of the rhachis (2); and (3) the lower half of a lower palea, showing its form (rounded on the back, not keeled.)
BRIZOPYRUM.- A pistillate spikelet of B. spicatum, enlarged (1); a flower from the same (2); and a flower from a staminate spikelet (3).
POA.- Panicle of P. compressa, reduced in size (1); a magnified spikelet (2); a separate flower more magnified (3); a lower palea cut across and somewhat outspread (4).
ERAGROSTIS.- A spikelet of E. pilosa, enlarged (1); the same, from which the glumes and all of six lower flowers except the upper palea have fallen away (2); a magnified flower, open (3); the lower palea of the same outspread (4).
BRIZA.- A spikelet of B. media, enlarged (1); a separate flower (2).
FESTUCA.- A spikelet of F. elatio. enlarged (1); a separate flower (2); lower part of a lower palea, outspread (3).
BROMUS.- A spikelet of B. secalinus, of Chess (1); a separate flower, enlarged (2).

TAB. V.

UNIOLA.- A spikelet of U. latifolia of about the natural size (1); a flower, enlarged (2); empty lower palea of the lowest (sterile) flower (3).
PHRAGMITES.- A spikelet of P. communis, enlarged (1); one of the perfect flowers, enlarged (2); and the lowest flower (3), which has stamens only.
ARUNDINARIA.- A spikelet of A. macrosperma (1); a separate flower, magnified (2).
LEPTURUS.- Portion of the spike of L. paniculatus, enlarged (1); a flower magnified (2).
LOLIUM.- Portion of the spike of L. temulentum (1); a separate flower, magnified (2).
TRITICUM.- Portion of the spike of T. repens, or Couch-Grass, of about the natural size (1); a flower magnified (2).
HORDEUM.- The three one-flowered spikelets from one joint of the spike of H. jubatum, with their awn-like glumes, the lateral flowers abortive and neutral, the middle one alone perfect (1); this perfect flower (with an awn-like rudiment) open and enlarged (2).
ELYMUS.- The two spikelets of one joint of the spike of E. Virginicus, about the natural size (1); the glumes and the flowers of one spikelet, enlarged and displayed (2); and an open flower, more magnified (3).
GYMNOSTICHUM.- A spikelet of G. Hystrix (1), and an expanded flower, magnified (2).

TAB. VI.

AIRA.- Panicle of A. flexuosa (1); a spikelet, magnified, the parts displayed (2); and one of the flowers detached and open (3).
DANTHONIA.- Panicle of D. spicata (1); a spikelet enlarged (2); and a separate flower from the same (3).
TRISETUM.- A spikelet of T. subspicatum, var. molle, expanded and magnified (1); and a separate open flower (2).
AVENA.- A spikelet of A. striata displayed and magnified (1); and a separate flower (2).

733
EXPLANATION OF THE PLATES.

MELICA.- A magnified spikelet of M. mutica, expanded, showing the glumes, two perfect flowers, and an abortive one.
GYCERIA.- A magnified spikelet of G. nervata (1); a separate flower with one joint of the rhachis (2); and (3) the lower half of a lower palea, showing its form (rounded on the back, not keeled.)
BRIZOPYRUM.- A pistillate spikelet of B. spicatum, enlarged (1); a flower from the same (2); and a flower from a staminate spikelet (3).
POA.- Panicle of P. compressa, reduced in size (1); a magnified spikelet (2); a separate flower more magnified (3); a lower palea cut across and somewhat outspread (4).
ERAGROSTIS.- A spikelet of E. pilosa, enlarged (1); the same, from which the glumes and all of six lower flowers except the upper palea have fallen away (2); a magnified flower, open (3); the lower palea of the same outspread (4).
BRIZA.- A spikelet of B. media, enlarged (1); a separate flower (2).
FESTUCA.- A spikelet of F. elatio. enlarged (1); a separate flower (2); lower part of a lower palea, outspread (3).
BROMUS.- A spikelet of B. secalinus, of Chess (1); a separate flower, enlarged (2).

TAB. V.

UNIOLA.- A spikelet of U. latifolia of about the natural size (1); a flower, enlarged (2); empty lower palea of the lowest (serile) flower (3).
PHRAGMITES.- A spikelet of P. communis, enlarged (1); one of the perfect flowers, enlarged (2); and the lowest flower (3), which has stamens only.
ARUNDINARIA.- A spikelet of A. macrosperma (1); a separate flower, magnified (2).
LEPTURUS.- Portion of the spike of L. paniculatus, enlarged (1); a flower magnified (2).
LOLIUM.- Portion of the spike of L. temulentum (1); a separate flower, magnified (2).
TRITICUM.- Portion of the spike of T. repens, or Couch-Grass, of about the natural size (1); a flower magnified (2).
HORDEUM.- The three one-flowered spikelets from one joint of the spike of H. jubatum, with their awn-like glumes, the lateral flowers abortive and neutral, the middle one alone perfect (1); this perfect flower (with an awn-like rudiment) open and enlarged (2).
ELYMUS.- The two spikelets of one joint of the spike of E. Virginicus, about the natural size (1); the glumes and the flowers of one spikelet, enlarged and displayed (2); and an open flower, more magnified (3).
GYMNOSTICHUM.- A spikelet of G. Hystrix (1), and an expanded flower, magnified (2).

TAB. VI.

AIRA.- Panicle of A. flexuosa (1); a spikelet, magnified, the parts displayed (2); and one of the flowers detached and open (3).
DANTHONIA.- Panicle of D. spicata (1); a spikelet enlarged (2); and a separate flower from the same (3).
TRISETUM.- A spikelet of T. subspicatum, var. molle, expanded and magnified (1); and a separate open flower (2).
AVENA.- A spikelet of A. striata displayed and magnified (1); and a separate flower (2).