Poa secunda subsp. juncifolia

(Scribn.) Soreng
Common names: Alkali bluegrass Big bluegrass Nevada bluegrass
Synonyms: Poa ampla Poa nevadensis var. juncifolia Poa nevadensis Poa juncifolia var. atnpla Poa juncifolia
Treatment appears in FNA Volume 24. Treatment on page 586.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Basal leaf tufts usually medium to robust, infrequently tiny. Basal branching mainly extravaginal. Culms 30-120 cm. Ligules of culm leaves 0.5-6 mm, those of the innovations 0.5-2 mm, scabrous, apices truncate to obtuse; blades 1-3(5) mm, moderately thick to thick, slightly lax to firm, tending to hold their form and persist. Panicles (4)10-25(30) cm, narrowly lanceoloid, contracted, congested; branches erect, scabrous. Spikelets (4)7-10 mm, lengths 4-5 times widths, narrowly lanceolate, subterete; calluses glabrous; lemmas sparsely to moderately scabridulous to scabrous, usually glabrous, keels and marginal veins infrequently crisply puberulent on the basal 1/4, hairs usually shorter than 0.2 mm; paleas glabrous. 2n = 42, 56, 60, 61, 62, 63, 64, ca. 65, ca. 66, 70, 78, 84, ca. 97.

Discussion

Poa secunda subsp. juncifolia is usually more robust than subsp. secunda, and generally inhabits moister and sometimes saline habitats. It comprises two fairly distinct variants: a robust upland variant that is frequently used for revegetation (P. ampla Merr., Big Bluegrass) that grows in deep, rich, montane soils; and a riparian and wet meadow variant (P. juncifolia Scribn., Alkali Bluegrass). Apart from generally having glabrous lemmas, short ligules on the vegetative shoots, and leaf blades that hold their form better, P. secunda subsp. juncifolia differs anatomically in the predominance of sinuous-walled, rectangular long cells in the blade epidermis; smooth-walled, fusiform long cells are predominant in P. secunda subsp. secunda. Plants with glabrous lemmas and long ligules on the vegetative shoots have been called P. nevadensis Vasey ex Scribn.; they are intermediate between the subspecies. Chromosome numbers for P. secunda subsp. juncifolia center on 2n = 63, indicating a high degree of apomixis.

Selected References

None.

Lower Taxa

None.
Robert J. Soreng +
(Scribn.) Soreng +
Alkali bluegrass +, Big bluegrass +  and Nevada bluegrass +
Maine +, Colo. +, N.Mex. +, Wash. +, Wyo. +, Utah +, Calif. +, Mich. +, Idaho +, Mont. +, Alta. +, B.C. +, N.W.T. +, Ont. +, Que. +, Sask. +, Yukon +, Minn. +, N.Dak. +, Nebr. +, Okla. +, S.Dak. +, Ariz. +, Alaska +, Nev. +  and Oreg. +
Poa ampla +, Poa nevadensis var. juncifolia +, Poa nevadensis +, Poa juncifolia var. atnpla +  and Poa juncifolia +
Poa secunda subsp. juncifolia +
Poa secunda +
subspecies +