FLORA 07 THE DISTRICT OP COLUMBIA. 45
S. SOBGHASTBTJM
9. PANICTJM L
Plants annual. Panicles open.
Spikelets warty. Plants glabrous 13. P. verrucosum.
Spikelets smooth.
Sheaths glabrous; first glume only one-fourth as long as the dpikelet, truncate.
1. P. dichotomiflorum, Sheaths hirsute; first glume as much as half the length of the spikelet, pointed.
(Capillaria.)
Panicles drooping; spikelets 4.5-5 mm. long 6. P. miliaceum.
Panicles erect; spikelets not over 3.5 mm. long.
Spikelets 3-3.5 mm. long, acuminate; panicles narrow, usually less than half as broad as long, or sometimes spreading at maturity 2. P. flexile.
Spikelets about 2 mm. long, acutish but not acuminate; panicles as broad ae long.
Panicles more than half the length of the entire plant; culms rather stout, erect or ascending 5. P. capillare.
Panicles not more than one-third the length of the entire plant; culms erect or decumbent-spreading.
Culms stout, soon decumbent-spreading; blades about 1 cm. wide,
3. P. gattingeri.
Culms slender, erect, zigzag below; blades not over 6 mm. wide.
4. P. philadelphicum.
Plants perennial.
Spikelets short-pediceled, on short branchlets along the main branches of the panicle, pointed. Sheaths keeled. (Agrostoidea.)
Rootstocks present; culms but little compressed 12. P. anceps.
Rootstocks wanting; culms strongly compressed, with keeled sheathe.
Ligule ciliate, 2-3 mm. long; panicle much exceeding the upper leaves.
11. P. longifolium.
Ligule erose or lacerate but not ciliate; panicle not much longer than the upper leaves.
Fruit stipitate; spikelets conspicuously secund; panicle usually purple.
10. P stipitatum.
Fruit not stipitate; spikelets not conspicuously Fecund; panicle green or slightly tinged with purple.
Spikelets 1.8-2 mm. long; panicle branches ascending or spreading.
8. P. agrostoides, Spikelets about 2,.5 mm. long; panicle branches erect or nearly so.
9. P. condensum.
FLORA OF THE DISTRICT OF COLUMBIA. 75
Spikelets long-pediceled, in an open panicle.
Bootstocks present; c ul ma stout and erect; no winter rosette of leaves formed.
Spikeleta 4-4.5 mm. long (rarely 3.6-6 mm.), beaked; first glume two-thirds the length of the spikelet or more 7. P. virgatum.
Spikeleta not over 3.2 mm. long, not beaked; first glume about half the length of the spikelet 7a. P. virgatum cubense.
Bootstocks wanting; plants usually forming a winter rosette of basal leaves.
Vernal phase blooming in the early summer, the culms simple, with open terminal panicles; the autumnal phase much branched, the panicles reduced and more or less included in the sheaths. (Subgenus Dichantheliuh.)
Blades elongate, not over 5 mm. wide, 20 times as long as wide, (Depau- febata.) (See P. bicknellii and P. acukatum.)
Spikelets about 3.6 mm. long, beaked , .14. P. depauperatum.
Spikelets 2-2.7 mm. long, not beaked.
Sheaths pilose 15. P. linearifolium.
Sheaths glabrous 16. P. werneri.
Blades not elongate, usually not more than 10 times as long as wide.
Spikelets glabrous.
Spikelets about 1.5 mm. long. Nodes bearded; autumnal phase much branched, reclining 19. P. microcarpon.
Spikelets 2 mm. long or more.
Culms soon prostrate, the autumnal phase vinelike 26. P. lucidum.
Culms erect, the autumnal phase sometimes reclining but not vinelike.
Spikelets about 2.5 mm. long, pointed beyond the fruit.
25. P. yadkinense, Spikelets 2 mm. long, not pointed beyond the fruit.
Nodes glabrous; autumnal phase erect, branched like a little tree.
23. P. dichotomum.
Nodes, at least the lowest, bearded; autumnal phase top-heavy, reclining 24. P. barbulatum.
Spikelets pubescent (sparsely so in P. scribnerianum).
Spikelets 3 mm. long or more.
Ligule 3-4 mm. long; blades velvety beneath, firm 48, P. ravenelii.
Ligule obsolete; blades not velvety beneath (except in P. boscii molle).
Nodes bearded; spikelets 4-4.5 mm. long.
Blades glabrous or nearly so on both surfaces 60, P. boscii.
Blades velvety beneath ... 50a. P. boscii molle.
Nodes not bearded; spikelets mostly less than 4 mm. long.
Blades 1.5-4 cm. wide, cordate-clasping.
Sheaths glabrous; blades minutely ciliate at base.
49. P. latifolium.
Sheaths, at least the lower, tuberculate-hispid; blades not ciliate at base 48. P. elandestinum.
Blades rarely over 1 cm. wide, not cordate-clasping.
Pubescence ascending; spikelets 3.5-4 mm. long.
42. P. oligosanthes.
Pubescence spreading; spikelets 3.2-3.3 mm. long
Spikelets obtuse, 3.2-3.3 mm. long 41. P. scribnerianum.
Spikelets acute, 3 mm. long... 45, P aculeatum.
Spikelets less than 3 mm. long (see J\ elandestinum).
Sheaths retroreely pilose; plants light green, forming soft mats.
17. P. xalapense.
Sheaths not retroreely pilose; plants erect, spreading or finally prostrate but not forming soft mats a, aa-
A. Ligule manifest, 2-5 mm. long (1-1.5 mm. long in P. tmgetarum).
Sheaths glabrous or the lowest sometimes pubescent.
Panicle narrow, one-fourth to one-third as wide as long 27. P. spretum.
Panicle open, nearly as wide as long 28. P. lindheimeri.
Sheaths pubescent.
Spikelets 2.2-2,4 mm. long.
Pubescence on culms horizontally spreading; autumnal phase freely branching.
38. P vlllosissimuia.
Pubescence on culms appressed or ascending; autumnal phase rather sparingly branching 34. P. psendojrubescens.
. Spikelets less than 2 mm. long.
Vernal blades glabrous or nearly bo on the upper surface.
Ligule 1-1.6 mm, long; culm crisp-puberulent 36. P. tsugetorum.
Ligule 4-5 mm. long; culm papillose-pilose or becoming glabrous.
32. P. tennesseense.
Vernal blades pubescent on the upper surface.
Spikelets 1.3-1.6 mm. long; vernal blades long-pilose on the upper surface.
Autumnal phase widely decumbent-spreading, forming a mat, the vernal culms soon geniculate-spreading; plants grayish olivaceous.
30. P. albemarlense.
Autumnal phase erect, not forming a mat; plants yellowish green.
29. P. meridionale.
Spikelets 1.6-1.8 mm. long; vernal blades appressed-pubescent.
Blades stiff, erect 31. P. hnachucae.
Blades lax, spreading 31a. P. huachucae silvlcola, AA. Ligule obsolete or less than 1 mm. long.
Nodes bearded.
Blades velvety • 20. P. annulum.
Blades glabrous, or only the lower pubescent.
Sheaths and upper nodes glabrous 22. P. clutei.
Sheaths, at least the lower ones, and all the nodes pubescent.
21. P. mattamuskee tense.
Nodes not bearded.
Plants densely gray-velvety throughout, a viscid glabrous ring below the nodes.
44. P. scoparium.
Plants not gray-velvety.
Sheaths, or some of them, pilose or hispid.
Pubescence papillose-hispid 46. P. clandestinum.
Pubescence ascending-pilose.
Spikelets 2 mm. long 35. P. addisonii.
Spikelets 1.3 mm. long 37a. P. columbianum thinium.
Sheaths glabrous or only puberulent.
Spikelets spheric, not over 1.8 mm. long. Blades with a thin white carti- laginous margin.
Culms spreading; panicle as broad as long 38. P. sphaerocarpon.
Culms erect; panicle two-thirds as broad as long 39. P. polyanthes.
Spikelets not spheric.
Spikelets 2.5 mm. long.
Upper blades elongate, narrowed toward the base 18. P. bicknellii.
Upper blades not elongate, cordate at base.
Culms crisp-puberulent; blades usually less than 1 cm, wide.
46. P. ashei.
Culms glabrous; blades usually 1.5 era. wide or more.
47. P. commutatum.
FLORA OF THE DISTRICT OS" COLUMBIA. 77
Spikelets less than 2 mm. long.
Culms crisp-puberulent 87. P. columbianum.
Culms glabrous.
Nodes glabrous; culms delicate, sparingly branching.
40. P. ensiiolium.
Nodes bearded; culms slender but not delicate, very freely branching.
19. P microcarpon.
I. Panicum dichotomlflorum Michx.
Common in moist ground and embankments; a weed in cultivated soil. Aug.-Sept.
Eastern and middle states. (P. proli/erum of Ward's Flora,) 3 Panicum flexile (G&ttinger) Scribn.
Moist sandy soil; infrequent in our region. Sept. Eastern and middle states.
& Panicum gattingeri Nash.
Open and waste ground; frequent; a weed in cultivated soil. Sept. Eastern and middle states.
4 Panicum philadelptaicum Bernh.
Open sandy or argillaceous soil; common. Aug.-Sept, Eastern and middle states.
5. Panicum capillare L. Witch grass.
Open ground, fields, and waste places; common. Sept. A weed in cultivated soil.
Atlantic Coast to the Rocky Mis.
6. Panicum miliaceum L. Hog millkt. Broomcorn millet.
A weed in waste ground; rare. July-Aug. Escaped from cultivation in the north- eastern and middle states; native of Eur.
7. Panicum virgatum L.
Open moist ground and open woods; frequent, especially near the Potomac. July- Aug. Atlantic Coast to the Rocky Mts.
7a. Panicum virgatum cubense Griseb.
Boggy pine woods; infrequent; College Park and Beltsville. July-Aug. Atlantic Coastal Plain.
8. Panicum agrostoides Spreng.
Wet meadows and swales; infrequent. Aug. Eastern U.S.
9. Panicum condensum Nash.
Swales near the Potomac below Washington; rare. Sept.-Oct. Atlantic Coastal Plain.
10. Panicum stipitatum Nash.
Wet meadows and swales near the Eastern Branch and Potomac; frequent. Sept.
Eastern U. S.
II. Panicum longffolium Torr.
Moist sandy or gravelly ground in the valley of the Eastern Branch; infrequent.
Aug. Atlantic and Gulf states.
12. Panicum anceps Michx.
Moist open ground or open woods; common. Aug. Eastern U. 8.
13. Panicum verrucosum Muhl.
Wet sandy woods or shaded ditches; frequent from Takoma Park eastward. Aug.- . Sept. Eastern and southern states and in northern Ind.
14. Panicum depauperatnm Muhl.
Sterile woods; frequent. Eastern IT. S.
1$, Panicum llneaiifolium Scribn.
Dry woods along the north side of the Potomac; frequent. Eastern U.S.
16. Panicum werneri Scribn.
Pine woods; near Paint Creek. Me. to Mo. and Md.
17. Panicum xalapense H. B. K.
Rich alluvial woods or open ground along the Potomac from District Line to Great Falls; frequent. Southern states, north to Md. (P. laxijtorum of Britt. & Brown,
Illustr. Fl.)
18. Paul cum bicknellil Nash.
Rocky woods between Chevy Chase, Glen Echo, and Great Falls; near Paint Creek, west of Beltsville; infrequent. Eastern U. S.
Associated with Kalmia latifolia, Panicum asfiei, and Antennaria.
10. Panicum microcarpon Muhl.
Swampy borders and swales or alluvial stream banks; common, especially eastward.
Eastern U, S, (P. barbulatum of Britton'a Manual.)
Forming great tangled masses with conspicuously bearded nodes and small divari- cate blades on slender scorpioid branchlets.
20. Panicum annulum Aahe.
Rather rich rocky woods, between Chevy Chase, Cleveland Park, and Great Falls;
infrequent. Atlantic states, above the Coastal Plain, and in Mo. and Miss.
21. Panicum mattamuskeetense Aahe.
Magnolia bogs; Beltsville and east of Hyattsville; rare. Atlantic Coastal Plain, Long IbI. to N. C.
32. Panicum clutel Nash.
Boggy swale, Kenilworth; rare. Atlantic Coastal Plain, Mass. to N. C.
Intergrades with P. mattamnskeetense; possibly only a form of that.
23. Panicum dichotomum L.
Dry and sterile woods; common. Eastern U. S.
24. Panicum barbulatum Michx.
Sterile and rocky woods; commoner than P. dichotomum. Eastern U, S.
20. Panicum yadkinense Ashe.
Moist thickets and brushy places along streamlets; frequent. Southern Atlantic states, north to Pa.
26. Panicum lucldum Ashe.
Magnolia bogs and boggy spots in pine woods; Takoma Park and eastward; found in 1898 at Fort Myer. Southern states, north to N. Y.
Forming large clumps, the vinelike culms with spreading glossy blades prostrate among sphagnum and underbrush.
27. Panicum spxetum Schult.
Wet sandy open ground; College Park; rare. Atlantic Coastal Plain, Me. to Tex.
28. Panicum lindheimeri Nash.
Wet sandy meadows or low open woods; common. Atlantic Coast to the Great Plains.
29. Panicum meridionale Ashe.
Sandy or rocky woods and copses; frequent. R. I. to Ala.
30. Panicum albemarlense Ashe.
Low sandy wood borders and clearings; frequent southeastward below the fall line.
Eastern U. S.
31. Panicum huachucae Asho.
Open grassy ground; infrequent. Mississippi Valley and northeastward.
31a. Panicum huachucae sllvicola Hitchc. & Chase.
Open woods and clearings; common. Eastern U. S.
32. Panicum tennesseense Ashe.
Wood borders and roadsides, usually in rather moist ground; common, especially in the vicinity of the Potomac above Washington. Atlantic Coast to the Rocky Mts.
33. Panicum villosissimum Nash.
Dry or sandy open woods and clearings; common. Eastern U. S.
34. Panicum pseudopubescens Nash.
Dry sandy open woods; found at Kenilworth in 1899. Southern Atlantic states to Conn. (P. ovale of Gray's Manual.)
FLORA OF THE DISTRICT 07 COLUMBIA. 79
36. Panicum addisonli Nash.
Dry sandy pine woods near the junction of Bladeneburg Road and Carters Lane, east of Hyattsville. Coastal Plain, Mass. to S. C.
A characteristic species of the sand-barrens of the Atlantic Coast; in our region associated with sand-barren species*.
36. Panicnm tsugetorum Nash.
Sandy woods; below the fall line; infrequent. Northeastern TJ. S., south to Va.
37. Panicum columbianum Seribn.
Rocky and sandy woods, especially eastward; frequent. Northeastern D. S.f south to Va.
37a. Panicum columbianum thinium Hitchc. & Chase.
Dry sands of the flood plain in a loop of the Eastern Branch, east of Hyattsville.
Mass. to Va.
A characteristic plant of the sand barrens of the Atlantic Coast.
38. Panicum sphaerocarpon Ell.
Open ground everywhere, especially in sandy soil. Eastern U. S.
39. Panicum polyanthes Schult.
Moist ground, wood borders, and clearings; frequent, especially below the fall line.
Southern Atlantic states to N. J, 40. Panicum ensifolium Baldw.
Open spot in white sand magnolia bog, Powdermill Swamp. Atlantic Coastal Plain, north to N. J.
41. Panicum seribnerianum Nash.
Sandy open ground; frequent. Me. to Md. and westward. (P. pauciflorum of Ward'a Flora.)
42. Panicum oligosanthes Schult.
Sandy, usually moiat, open woods; below the fall line; infrequent. Southern states, north to N. J.
43. Panicum ravenelii Seribn, & Men.
Sandy or rocky open woods; frequent. Southern states, north to Md.
44. Panicum scoparium Lam.
Wet open ground, wood borders, and along streams; below the fall line; common.
Southern states, north to Mass. (P. vi&cidum Ell.) 45. Panicum aculeatum Hitchc. & Chase.
Boggy wood borders and thickets; Takoma Park (type locality), Bright wood, and east of Hyattsville. Coastal Plain from Long Isl. to N. C.
A rare species.
46. Panicum ashei Pearson.
Sterile or rocky oak and pine woods; common. Eastern U. S.
A characteristic plant of laurel and blueberry hillsides.
47. Panicum commutatum Schult.
In lose sterile woods than those occupied by P. asfiei, the two occasionally growing together; common. Eastern U. S.
43. Panicum clandestinum L
Moist open ground and wood borders and along streamlets; common. Eastern XT. S.
The ripe grains remaining in the crowded sheaths well into the winter afford food for birds.
48. Panicum latifolium L.
Rich rocky woods along the Potomac above Washington; frequent. Eastern U. S.
(P. maerocarpon LeConte.) 50. Panicum boscii Poir.
Wooded slopes everywhere; common. Eastern U. S. (P. porterianum Nash.) 50a, Panicnm boscii molle (Vasey) Hitchc. & Chase.
Same habitat as the species; commoner. Eastern U. S. (P. latifolium molle Vasey.)
10. ECHINOCHIaOA Beau v.
Sheatha glabrous; awns rarely over 3 cm. long; panicle rarely over 20 cm. long, not drooping 1. E. crusgalli Sheaths hirsute; awns 3-5 cm. long; panicle drooping, commonly 30-40 cm. long.
2. E. walterl.
1. Echinochloa crasgalli (L.) Beau v. Babnyabd grass. Cocispur.
Moist low open ground; common; an introduced weed. Aug.-Sept. Throughout the U. S., except in the northern tier of states; native of Eur. (Panicum crusgalli L.)
8. Echinochloa waiter! (Pursh) Nash.
In swales; Potomac fiats and southward; infrequent. Aug.-Sept. Atlantic Coastal Plain, and about the head of Lake Michigan. (Panicurn walteri Pursh; P.
crusyalli hispidum A. Gray.)
11. CHAETOCHLOA Scribn.
Plants perennial by short knotty rootstocks 1. C. genicuiata, Plants annual.
Bristles downwardly barbed 3. C. verticillata.
Bristles upwardly barbed.
Bristles 5 or more in each cluster; spikes yellowish 2. C. lutescens.
Bristles 1-3 in each cluster; spikes green or purplish.
Spikelet articulate below the irlumo.^, the complete ^pikelet shelling out, leaving a cuplike receptacle 4. C viridis.
Spikelet articulate above the glumes, only the fruit shelling out, leaving the persistent glumes and eterile lemma 6. C. italics,
1. Chaetochloa genicuiata (Lam.) Mi lisp. & Chase.
Moist meadows and along ditches; frequent. Sept. Eastern U. 8. (Setaria imberbis Roem. & Schult.; C. imberbis Scribn.)
2. Chaetochloa lutescens (Weigel) Stuntz. Yellow foxtail.
Open waste and cultivated ground everywhere. July-Sept. Common east of the Rocky Mts., rare on the Pacific Coast; introduced from Eur.
A troublesome weed in lawns and gardens. In mowed lawns the culms become prostrate and fruit when 10-20 cm. long. (Setaria glauca and Chaetochloa glauca of authors.)
3. Chaetochloa verticillata (L.) Scribn.
Open waste ground; uncommon. July-Aug. Eastern and middle states. Intro- duced from Eur. (Setaria verticillata Beauv.)
4. Chaetochloa viridis (L.) Scribn. Gbeen foxtail.
Open waste ground and river flats; frequent. June-Aug. Throughout the U.S.;
introduced from Eur. (Setaria viridis Beauv.) Not an aggressive weed in this region.
5. Chaetochloa italica (L.) Scribn. Millet.
Dumping grounds and along railroads. July. Throughout the U. S., except in the mountains, as an escape from cultivation; native of Eur. (Setaria italica Roem. &
Schult.)
Plants growing spontaneously vary in size from 30 cm. or less to 1.5 meters tall.
12, CENCBRUS L,
1. Cenchrus pauciflorus Benth. Sandbur.
Sandy ground, along railroads and trolley tracks to the eastward; common in the vicinity of Bennings. July-Sept. Throughout the U. S. (C. tribuloides of Ward's Flora; C. carolinianus of recent manuals, not Walt.)
FLORA OF THE DISTRICT OF COLUMBIA. 81