Spikelets 1-flowered, not jointed on the pedicels. Outer glumes unequal, often bristle-pointed; the flowering glume tipped with three awns; the palet much smaller. Otherwise much as in Stipa.--Culms branching; leaves narrow, often involute. Spikelets in simple or panicled racemes or spikes. Grain linear. All grow in sterile, dry soil, and all ours have the awns naked and persistent, and flower late. (Name from _arista_, a beard or awn.)

[*] _Awns separate to the base, not jointed with the glume._

[+] _Awns very unequal; the much shorter or minute lateral ones erect, the elongated middle one horizontal or turned downward; low (5--18'

high) and branching, mostly tufted annuals, and the spikelets in nearly simple spikes._

[++] _Middle awn more or less coiled._

1. A. ramosissima, Engelm. Culms much branched; spikes loose, usually exserted; lower glumes 6--10" long, exceeding the upper, usually rather strongly 3--5-nerved; middle awn 1' long, soon abruptly hooked-recurved, the lateral ones 1--3" long.--Dry prairies of Ill., Ky., and Mo.--Also var. UNIARISTaTA, Engelm., with the lateral awns wanting.

2. A. basiramea, Engelm. Spikes closer, mostly enclosed at base, at all the lower nodes (even to the base of the culm) very short and sessile; lower glumes 4--8" long, mostly thin and 1-nerved or rather faintly 3-nerved; middle awn very slender, 6" long, the lateral 2" long.--Ill.

to Neb. and Minn.

3. A. dichotoma, Michx. (POVERTY GRa.s.s.) Culms low, very slender, much branched throughout, ascending; spikelets in narrow strict simple or compound spikes; lower glumes nearly equal (3--4" long), longer than the flowering glume and fully equalling its minute lateral awns (or unequal and shorter, in var. CURTiSSII, Gray), the soon reflexed middle awn about as long.--Dry, sandy or gravelly fields; common, Maine to Ill., and southward.

[++][++] _Middle awn nearly straight (not coiled)._

4. A. gracilis, Ell. Culms slender, erect (6--18' high), naked above and terminating in a slender raceme- or spike-like virgate panicle; lower glumes 1-nerved, about the length of the upper, the exserted lateral awns varying from one third to fully half the length of the horizontally bent middle one: or in var. DEPAUPERaTA, from one fifth to one third its length.--Sandy soil, coast of Ma.s.s., and from Ill. southward.--Middle awn 3--9" long in the ordinary forms, but not rarely shorter, and very variable often on the same plant.

[+][+] _Awns all diverging and alike, or the lateral ones moderately shorter, rarely at all coiled._

[++] _Glumes equal or the middle one longer._

5. A. stricta, Michx. Culms (2--3 high) densely tufted from a _perennial_ root, bearing a (1) long _spiked panicle_; leaves involute-thread-form, long, rigid, sometimes downy; awns about the length of the glumes (6") or the lateral one third shorter.--Va. and southward.

6. A. oligantha, Michx. Culms (6--20' high) tufted from an _annual_ root, bearing a _loosely few-flowered raceme_; leaves short, somewhat involute when dry; lower glume 3--5-nerved (nearly 1' long); _awns capillary_, 1--3' long, much exceeding the slender spikelet.--Va. to Ill., and common southwestward.

7. A. purpurea, Nutt. Perennial; culms (1 high or less) densely tufted, spreading; leaves revolute and filiform, short; panicle loose, of rather few slender-pedicellate spikelets; lower glumes thin, 1-nerved, loose, the outer about half the length of the inner, which is 8--10" long; awns 2--4" long.--Minn. and Dak. to Tex.--Very variable.

[++][++] _Middle glume shorter than the lower; perennials, simple-stemmed, 2--4 high._

8. A. purpurascens, Poir. (Pl. 8.) _Glabrous_; leaves long, rather involute; spikelets in a (10--18') long spiked panicle; lower glumes 1-nerved; _awns much longer than the spikelet_, the middle one about 1'

long.--Ma.s.s. to Mich., Minn., and southward; common.

9. A. lanata, Poir. Tall and stout; _leaves_ tardily involute, _rough_ above, rigid; _sheaths woolly_; panicle (1--2 long) spike-like or more compound and open; glumes 1-nerved, 6--8" long; middle awn 1'

long.--Del. to Fla.

[*][*] _Awns united below into one, jointed with the apex of the glume; root annual._

10. A. tuberculsa, Nutt. Culm branched below (6--18' high), tumid at the joints; panicles rigid, loose, the branches in pairs, one of them short and about 2-flowered, the other elongated and several-flowered; lower glumes (1' long, including their slender-awned tips) longer than the upper, which is tipped with the common stalk (about its own length) of the 3 equal divergently-bent awns (1--2' long) twisting together at the base.--Sandy soil, E. Ma.s.s. to N. J.; also Wisc., Minn., and southward.

20. STPA, L. FEATHER-GRa.s.s. (Pl. 8.)

Spikelets 1-flowered, terete; the flower falling away at maturity (with the conspicuous obconical bearded and often sharp-pointed callus) from the membranaceous persistent lower glumes. Fertile glumes coriaceous, cylindrical-involute and closely embracing the smaller palet and the cylindrical grain, having a long and twisted or tortuous simple awn jointed with its apex. Stamens mostly 3. Stigmas plumose.--Perennials, with narrow involute leaves and a loose panicle. (Name from st?p?, _tow_, in allusion to the flaxen appearance of the feathery awns of the original species. In our species the awn is naked.)

[*] _Callus or base of the flower short and blunt; lower glumes pointless._

1. S. Richardsnii, Link. Culm (1--2 high) and leaves slender; panicle loose (4--5' long), with slender few-flowered branches; lower glumes nearly equal, oblong, acutish (2--4" long), about equalling the p.u.b.escent linear-oblong fertile one, which bears a tortuous awn 6--9"

long.--Pleasant Mountain, near Sebago Lake, Maine, Mt. Marcy, N. Y., north sh.o.r.e of L. Superior, Mont., and northward.

[*][*] _Callus pungently pointed, at maturity villous-bearded; flowering glume slender and minutely bearded at the tip; empty glumes taper-pointed._

2. S. avenacea, L. (BLACK OAT-GRa.s.s.) (Pl. 8.) Culm slender (1--2 high); leaves almost bristle-form; _panicle open; fertile glume blackish, nearly as long as the lower ones_ (about 4" long); the awn bent above, twisted below (2--3' long).--Dry woods, S. New Eng. to Wisc., and southward.

3. S. spartea, Trin. (PORCUPINE GRa.s.s.) Culm rather stout (1--3 high); _panicle contracted; fertile glume linear_, --1' long (including the long callus), p.u.b.escent below, _shorter than the_ lanceolate slender subulate pointed greenish _lower glumes_; the twisted strong awn (3--7'

long), p.u.b.escent below, rough above.--Plains and prairies, from Ill. and N. Mich. northwestward.

4. S. viridula, Trin. Culms cl.u.s.tered, 1--3 high or more; panicle narrow and usually dense, 6--18' long; glumes very thin, 3--4" long; fertile glume usually somewhat silky, with a short callus; awn 1' long, slender, glabrous or a little p.u.b.escent below.--W. Minn., Dak., and southwestward.

21. ORYZoPSIS, Michx. MOUNTAIN RICE. (Pl. 8.)

Spikelets 1-flowered, nearly terete. Lower glumes herbaceous or thin-membranaceous, several-nerved, nearly equal, commonly rather longer than the oblong flower, which is deciduous at maturity, and with a very short obtuse callus or scar-like base. Flowering glume coriaceous, at length involute so as closely to enclose the equal palet and the oblong grain; a simple untwisted and deciduous awn jointed on its apex. Stamens 3. Squamulae 2 or 3, conspicuous. Stigmas plumose.--Perennials, with rigid leaves and a narrow raceme or panicle. Spikelets greenish, rather large. (Name composed of ????a, _rice_, and ????, _likeness_, from a fancied resemblance to that grain.)

[*] _Styles distinct, short; culm leafy to the summit; leaves broad and flat._

1. O. melanocarpa, Muhl. Leaves lanceolate, taper-pointed; sheaths bearded in the throat; panicle simple or sparingly branched; awn thrice the length of the blackish glume (nearly 1' long).--Rocky woods, N. Eng.

to Penn., Minn., Mo., and westward. Aug.--Culm 2--3 high.

[*][*] _Styles united below, slender; culms tufted, naked; leaves concave or involute._

2. O. asperiflia, Michx. (Pl. 8, fig. 1, 2.) Culms (9--18' high), with sheaths bearing a mere rudimentary blade, overtopped by the _long and rigid linear leaf from the base_; very simple panicle or raceme few-flowered; _awn 2--3 times the length of the rather hairy whitish glume_.--Hillsides, etc., in rich woods; common, N. Eng. to Minn., and northward. May.--Leaves without keels, rough-edged, pale beneath, lasting through the winter. Squamulae lanceolate, almost as long as the palet!

3. O. Canadensis, Torr. Culms slender (6--15' high), the lowest sheaths leaf-bearing; _leaves involute-thread-shaped_; panicle contracted (1--2'

long), the branches usually in pairs; glume p.u.b.escent, whitish; _awn short and very deciduous, or wanting_.--Rocky hills and dry plains, Maine to W. New Eng., the mountains of Penn., Wisc., Minn., and northward; rare. May.--Glumes 1--2" long, sometimes purplish.

22. MiLIUM, Tourn. MILLET-GRa.s.s. (Pl. 13.)

Spikelets 1-flowered, diffusely panicled, not jointed with their pedicels, consisting of 2 equal membranaceous convex and awnless persistent glumes, with a coriaceous awnless flowering glume and narrow palet. Stamens 3. Stigmas branched-plumose. Grain not grooved, enclosed in its glume and palet, all deciduous together. (The ancient Latin name of the Millet, which however belongs to a different genus, of uncertain meaning.)

1. M. effusum, L. Smooth perennial, 3--6 high; leaves broad and flat, thin; panicle spreading (6--9' long); flower ovoid-oblong.--Cold damp woods and mountain meadows, N. Eng. to Ill., and northward. June. (Eu.)

23. MUHLENBeRGIA, Schreber. DROP-SEED G. (Pl. 8.)

Spikelets 1-flowered, in contracted or rarely in open panicles. Empty glumes mostly acute or bristle-pointed, persistent, usually thin; the lower rather smaller or minute. Flower very short-stalked or sessile, the glume and palet usually minutely bearded at base, herbaceous, deciduous with the enclosed grain, often equal, the glume 3-nerved, mucronate or awned at the apex. Stamens 3. (Dedicated to the _Rev. Dr.

Henry Muhlenberg_, a distinguished American botanist of the early part of this century.)

-- 1. MUHLENBERGIA proper. _Panicles contracted or glomerate, on branching rigid culms from scaly creeping rootstocks; leaves short and narrow._

[*] _Flowering glume barely mucronate or sharp-pointed._

1. M. sobolifera, Trin. Culms ascending (1--2 high), rarely branching; the _simple contracted panicle very slender_ or filiform; lower _glumes barely pointed, almost equal, one third shorter than the flower_; flowering glume abruptly short-mucronate, equalling the palet.--Open rocky woods, Ma.s.s. to Mich., Minn., and southward. Aug.--Spikelets less than 1" long.

2. M. glomerata, Trin. Culms upright (1--3 high), sparingly branched or simple; _panicle_ (2--3' long) _oblong-linear, contracted into an interrupted glomerate spike_, long-peduncled, the branches sessile; _glumes awned_, nearly equal, and (with the bristle-like awn) about twice the length of the unequal very acute flowering glume and palet.--Bogs and wet rocks, common, especially northward. Aug.--Var.

RAMSA, Vasey. A stout strict much-branched leafy form, the lower glumes but little longer than the flower. Ill. to Dak.