Agrostis gigantea

Roth
Common names: Redtop Agrostide blanche
Introduced
Synonyms: Agrostis stolonifera var. major Agrostis gigantea var. ramosa Agrostis gigantea var. dispar Agrostis alba var. major
Treatment appears in FNA Volume 24. Treatment on page 641.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Plants perennial; rhizomatous, rhizomes to 25 cm, not stoloniferous. Culms 20-120 cm, erect, sometimes geniculate at the base, sometimes rooting at the lower nodes, with 4-7 nodes. Leaves mostly cauline, sheaths smooth or sparsely scabridulous; ligules longer than wide, dorsal surfaces usually scabrous, sometimes smooth, apices rounded to truncate, erose to lacerate, basal ligules 1-4.5 mm, upper ligules 2-7 mm; blades 4-10 cm long, 3-8 mm wide, flat. Panicles 8-25 (30) cm long, less than 1/2 the length of the culm, (1.5) 3-15 cm wide, erect, open, broadly ovate, exserted from the upper sheaths at maturity, lowest node with (1) 3-8 branches; branches scabrous, spreading during and after anthesis, usually some branches spikelet-bearing to the base, lower branches 4-9 cm, usually with many shorter secondary branches resulting in crowding of the spikelets, spikelets restricted to the distal 1/2 of the branches and not crowded in shade plants; pedicels 0.3-3.4 (4.2) mm. Spikelets narrowly ovate to lance¬olate, green and slightly to strongly suffused with purple. Glumes subequal, 1.7-3.2 mm, lanceolate, 1-veined, acute to apiculate; lower glumes scabrous on the distal 1/2 of the midvein; upper glumes scabridulous on the distal 1/2 of the midvein; callus hairs to 0.5 mm, sparse; lemmas 1.5-2.2 mm, opaque to translucent, smooth, 3-5-veined, veins usually obscure, sometimes prominent throughout or distally, often excurrent to 0.2 mm, apices usually acute, sometimes obtuse or truncate, usually unawned, rarely with a 0.4-1.5 (3) mm straight awn arising from near the apices to near the base; paleas 0.7-1.4 mm, about Vi the length of the lemmas, veins visible; anthers 3, 1-1.4 mm. Caryopses 1-1.5 mm; endosperm solid. 2n = 42.

Distribution

Conn., N.J., N.Y., Wash., Del., D.C., Wis., W.Va., Mass., Maine, N.H., R.I., Vt., Wyo., N.Mex., Tex., La., N.Dak., Nebr., Tenn., Pa., Okla., Alaska, Nev., Va., Colo., Calif., Ala., Ark., Ill., Ga., Ind., Iowa, Ariz., Idaho, Md., Ohio, Utah, Mo., Minn., Mich., Kans., Mont., Miss., S.C., Ky., Oreg., Alta., B.C., Greenland, Man., N.B., Nfld. and Labr. (Labr.), N.S., N.W.T., Ont., P.E.I., Que., Sask., Yukon

Discussion

Agrostis gigantea grows in fields, roadsides, ditches, and other disturbed habitats, mostly at lower elevations. It is a serious agricultural weed, as well as a valuable soil stabilizer. In the Flora region, its range extends from the subarctic to Mexico; it is considered to be native to Eurasia. It is more heat tolerant than most species of Agrostis.

Agrostis gigantea has been confused with A. stolonifera (see next), from which it differs in having rhizomes and a more open panicle. Agrostis stolonifera has elongated leafy stolons, mainly all above the surface, that root at the nodes, and the panicles are condensed and often less strongly pigmented than in A. gigantea. Its distribution tends to be more northern and coastal where ditches and pond margins are common habitats, and its stolons enable it to form loose mats. Agrostis gigantea is ecologically adapted to a more extreme climate—hot summers/cold winters and drought—than A. stolonifera. It is also similar to A. capillaris (p. 639) and A. castellana (p. 639); it differs from both in its longer ligules, from A. capillaris in its less open panicles with spikelets near the base of the branches, and from A. castellana in being more extensively rhizomatous.

When Agrostis gigantea grows in damp hollows under trees it becomes more like A. stolonifera, particularly when the inflorescence is young, not expanded, and pale. If the rootstock is not collected, identification is a major problem.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number."visible" is not a number.

... more about "Agrostis gigantea"
membranous +  and scarious +
not penicillate +
0.1 cm1 mm <br />0.001 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
awned +, truncate +  and entire +
truncate +, obtuse +, acute +, lacerate +  and rounded to truncate +
M.J. Harvey +
1 (?) +  and 3 (?) +
3 cm30 mm <br />0.03 m <br /> (?) +
straight +
basal +  and terminal +
geniculate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
rounded +  and keeled +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
not evident +
scabridulous +
cross +, linear +  and narrowly lanceolate +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
spikelike +
1 cm10 mm <br />0.01 m <br /> (?) +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
hairy +  and glabrous +
Redtop +  and Agrostide blanche +
geniculate +
20 cm200 mm <br />0.2 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
not woody +
3cm +  and 15cm +
Conn. +, N.J. +, N.Y. +, Wash. +, Del. +, D.C. +, Wis. +, W.Va. +, Mass. +, Maine +, N.H. +, R.I. +, Vt. +, Wyo. +, N.Mex. +, Tex. +, La. +, N.Dak. +, Nebr. +, Tenn. +, Pa. +, Okla. +, Alaska +, Nev. +, Va. +, Colo. +, Calif. +, Ala. +, Ark. +, Ill. +, Ga. +, Ind. +, Iowa +, Ariz. +, Idaho +, Md. +, Ohio +, Utah +, Mo. +, Minn. +, Mich. +, Kans. +, Mont. +, Miss. +, S.C. +, Ky. +, Oreg. +, Alta. +, B.C. +, Greenland +, Man. +, N.B. +, Nfld. and Labr. (Labr.) +, N.S. +, N.W.T. +, Ont. +, P.E.I. +, Que. +, Sask. +  and Yukon +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
sterile +  and bisexual +
compressed +
reduced +
(1)1.3-2(4) times longer than +
subtending +
acute +  and apiculate +
subequal +
0.17 cm1.7 mm <br />0.0017 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
uncinate +
diffuse +  and dense +
opaque +  and translucent +
pubescent +  and glabrous +
warty-tuberculate +  and scabridulous +
lanceolate +  and ovate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.22 cm2.2 mm <br />0.0022 m <br />) +
membranous +
membranous +
inconspicuous +
lanceolate +
4 cm40 mm <br />0.04 m <br /> (9 cm90 mm <br />0.09 m <br />) +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
concealed +  and prominent +
4 +  and 7 +
2 +  and 1 +
well-developed +
2-keeled +
minute +  and subequal +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
8cm +  and 25cm +
0 +  and 1/2 +
4.2 cm42 mm <br />0.042 m <br /> (?) +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.34 cm3.4 mm <br />0.0034 m <br />) +
dry +  and fleshy +
not prolonged +
hairy +  and glabrous +
scabridulous +  and smooth +
Introduced +
suffused with purple +  and green +
1 +  and 60 +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
Agrostis stolonifera var. major +, Agrostis gigantea var. ramosa +, Agrostis gigantea var. dispar +  and Agrostis alba var. major +
Agrostis gigantea +
Agrostis +
species +
membranous +
2 (?) +  and 5 (?) +
scabridulous +
not convergent +
prominent +  and obscure +
scabrous +  and scabridulous +
0 cm0 mm <br />0 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
aquatic +  and terrestrial +