Calamagrostis porteri

A. Gray
Common names: Porter's reedgrass
Endemic
Treatment appears in FNA Volume 24. Treatment on page 721.

Plants with sterile culms; loosely cespitose, with rhizomes 5-7+ cm long, 0.5-1 mm thick. Culms (60) 75-120 cm, unbranched, slightly scabrous; nodes 2-4 (5). Sheaths smooth or slightly scab¬rous; collars smooth or hairy; ligules (1) 2-5 (6) mm, truncate to obtuse, entire or lacerate; blades 8-40 cm long, (2) 3-8 (12) mm wide, flat, abaxial surfaces smooth or scabrous, adaxial surfaces smooth or slightly scabrous, occasionally with hairs. Panicles (5) 10-18 (22) cm long, 0.8-3 (7) cm wide, contracted to open, often slightly nodding, sometimes erect, green to pale-purple; branches (1.5) 2-7 (7.5) cm, scabrous, usually spikelet-bearing on the distal 1/2 - 2/3, sometimes to the base. Spikelets 4-5 (6) mm; rachilla prolongations 0.5-1 mm, hairs 1.5-2 (3.5) mm. Glumes rounded to slightly keeled, keels scabrous towards the apices, lateral-veins obscure to slightly prominent, not raised, apices acute to acuminate; callus hairs 1.5-2 (3) mm, 0.4-0.7 times as long as the lemmas, sparse; lemmas 3-4.5 mm, 0.5-1.5 (2) mm shorter than the glumes; awns 3-4 (4.5) mm, attached to the lower 1/10 – 3/10 of the lemmas, exserted, stout, easily distinguished from the callus hairs, strongly bent; anthers 2-2.5 mm. 2n = 56, 84-+104.

Distribution

Md., W.Va., Pa., Ohio, Mo., N.C., Tenn., Va., N.Y., Ark., Ill., Ga., Ind., Ky.

Discussion

Calamagrostis porteri grows in dry chestnut/oak forests, often on rocky ridgetops, piedmont bluffs, and slopes, at (100)600-1300 m. It is now restricted to the northeastern and central United States. Historically, its range extended from Missouri and Arkansas east to New York and Alabama. Flowering appears to be a response to disturbance; plants in undisturbed habitats remain vegetative and may go unnoticed. Thus the species may be more widespread and abundant than reported.

Calamagrostis porteri and C. rubescens (see next) appear to be closely related. They may be part of the general phenomenon of eastern and western vicariants. The apparently sterile C. perplexa (p. 726) is intermediate between C. porteri and C. canadensis (Greene 1980).

Selected References

None.

Key

1 Leaf blades glaucous on both surfaces; leaf collars glabrous Calamagrostis porteri subsp. insperata
1 Leaf blades light green and glaucous on the adaxial surfaces, darker green on the abaxial surfaces; leaf collars usually with prominent tufts of hair, rarely glabrous Calamagrostis porteri subsp. porteri

"decumbent" is not a number.

... more about "Calamagrostis porteri"
104 +, 84 +  and 56 +
membranous +  and scarious +
0.2 cm2 mm <br />0.002 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
Acute (?) +  and Acuminate (?) +
Kendrick L. Marr +, Richard J. Hebda +  and Craig W. Greenef +
A. Gray +
1 (?) +  and 3 (?) +
4.5 cm45 mm <br />0.045 m <br /> (?) +
straight +
attached +
exserted +  and lower +
distinguished +
1/10 +  and 3/10 +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
8 cm80 mm <br />0.08 m <br /> (40 cm400 mm <br />0.4 m <br />) +
not evident +
flat +  and involute +
3mm;8mm +
1.5 cm15 mm <br />0.015 m <br /> (?) +
appressed;more or less drooping +
spikelike +
0.4-0.7 times as long as the lemmas +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
hairy +  and smooth +
Porter's reedgrass +
ascending +  and erect +
75 cm750 mm <br />0.75 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
not woody +
Md. +, W.Va. +, Pa. +, Ohio +, Mo. +, N.C. +, Tenn. +, Va. +, N.Y. +, Ark. +, Ill. +, Ga. +, Ind. +  and Ky. +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
sterile +  and bisexual +
compressed +
reduced +
subtending +
rounded +  and slightly keeled +
subequal +
membranous +
3.5 cm35 mm <br />0.035 m <br /> (?) +
sparse +  and abundant +
uncinate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
not raised +, obscure +  and slightly prominent +
lanceolate +  and ovate +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
truncate +  and obtuse entire or lacerate +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
membranous +
inconspicuous +
lanceolate +
concealed +  and prominent +
2 +  and 4 +
2 +  and 1 +
hairy +  and glabrous +
2-keeled +
green +  and pale-purple +
10cm +  and 18cm +
erect +  and nodding +
spikelike +
0.8 cm8 mm <br />0.008 m <br /> (3 cm30 mm <br />0.03 m <br />) +
dry +  and fleshy +
1 +  and 60 +
compressed +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Calamagrostis porteri +
Calamagrostis +
species +
membranous +
parallel +  and converging +
obscure +  and prominent +
plant +  and cespitose +
aquatic +  and terrestrial +
0.5mm +  and 1mm +