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Key to Wisconsin Species of Juncus (Rushes)

1.  Inflorescence apparently lateral, with one erect bract appearing to be a continuation of the stem; sheaths without blades.

   2.  Stems in dense clumps; rhizomes absent; stamens 3 ................................... J. effusus

   2.  Stems single or few in loose clumps; rhizomes present; stamens 6.

      3.  Stems finely striate with long ridges; filaments longer than anthers; erect bract at

           least half as long as the stem below the inflorescence; inflorescense less than 2 cm

           long ........................................................................................................ J. filiformis

      3.  Stems smooth or irregularily ridged; filaments shorter than anthers; erect bract less

           than half as long as the stem; inflorescence usually more than 2 cm long

           .................................................................................................................. J. arcticus

1.  Inflorescence terminal, subtended by two or more spreading bracts or leaves; some or all sheaths with blades.

   4.  Inflorescence of 2-5 flowers; perianth whitish or pink [rare bog plant]

        ....................................................................................................................... J. stygius

   4.  Inflorescence of more than 5 flowers; perianth green, tan, or brown.

      5.  Leaves equitant (i.e. folded lengthwise on the midrib, the blades fitting together

           tongue-in -groove); stems strongly flattened [rare plant from Ashland Co.]

           ............................................................................................................... J. ensifolius

      5.  Leaves terete, tubular and hollow, or flat but not folded over.

         6.  Inflorescence at least one-fourth the height of the stem; bulblets present

              or plants annual.

            7.  Tufted annuals; leaves unranked, without auricles; flowers present, bulblets

                 absent; perianth subtended by small paired bracts ........................... J. bufonius

            7.  Rhizomatous perennials, often partially submersed; leaves two-ranked, with

                 auricles; many flowers replaced by small leafy bulblets; perianth without

                 subtending bracts .......................................................................... J. pelocarpus

         6.  Inflorescence usually less than one-fourth the height of the stem; perennials

              without bulblets.

            8.  Most or all flowers single, or paired, and subtended by small paired bracts;

                 flowers on pedicels in most species; blades flat or terete, not hollow and

                 septate.

               9.  Blades of some leaves arising near middle of stem; rhizome slender and

                    elongate; sepal tips obtuse and incurved.

                  10. Anther more than 1 mm long, more than twice as long as filament;

                       capsule ellipsoid-ovoid, about as long as perianth; stems dark green,

                       terete ............................................................................................. J. gerardii

                  10. Anther less than 1 mm long, less than twice as long as filament;

                       capsule obovoid, longer than the perianth; stems glaucous, slightly

                       flattened ................................................................................. J. compressus

               9.  Blades clustered near base of stem; rhizome short and densely branching

                    or absent; sepal tips acute or obtuse and erect to spreading.

                  11. Leaf blades terete; tepals erect; seeds often more than 0.6 mm long.

 

                     12. Sepals and petals obtuse; seeds without tails; stems usually single

                           ............................................................................................. J. squarrosus

                     12. Sepals and petals acute to acuminate; seeds with tails; stems

                           usually few to many.

                          13. Inflorescence greenish, with a stiff bract 1-8 cm long; seeds with a

                                tail at least half as long as body of seed; capsule green or golden-tan

                                ................................................................................................. J. vaseyi 

                          13. Inflorescence brownish, with flexuous bracts 5-25 cm long; seeds

                                with minute tails  ................................................................. J. greenei

                  11. Leaf blades flat, although often inrolled except at tip; tepals spreading,

                        green; seeds less than 0.6 mm long.

                     14. Auricles at summit of leaf sheath 3-6 mm long, pointed, membranous,

                           semi-transparent.

                        15. Capsule less than 3/4 as long as tepals, well-separated along branches

                              of inflorescence; most plants 70-90 cm tall ...................... J. anthelatus

                        15. Capsule about as long as tepals, more-or-less crowded together;

                              most plants less than 70 cm tall ............................................... J. tenuis

                    14. Auricles less than 1 mm long, blunt or pointed, thin or leathery.

                        16. Auricles thin, white or purplish; anthers 0.2-0.6 mm long;

                              tepals erect at fruiting stage .................................................. J. interior

                        16. Auricles leathery, yellowish; anthers 0.6-1 mm long; tepals

                              spreading in fruiting stage ..................................................... J. dudleyi

         8.  Most flowers in heads or glomerules of 3-many and lacking paired bracts at base;

              pedicels few or none; blades septate (i.e. tubular and hollow with

              cross-partitions), except in J. marginatus.

           17. Blades flat, relatively lax; stem slightly flattened, with bulbous base; anthers

                 purplish, shriveling after dehiscence ............................................ J. marginatus

           17. Blades septate, stiff; stems terete, without bulbous base; anthers yellow,

                 retaining same shape after dehiscence.

               18. Flowers in dense spherical heads; capsules subulate (i.e. widest at base,

                     long-tapered to apex); stems arising singly from threadlike tuber-bearing

                     rhizome.

                   19. Flowers reddish-brown; sepals 2.5-3.5 mm long, about as long as the

                         petals; auricles less than 2 mm long  ......................................... J. nodosus

                   19. Flowers green or dull brown; sepals 3.5-5.5 mm long, longer than the

                         petals; auricles more than 2 mm long .......................................... J. torreyi

               18. Flowers usually in hemispherical heads; capsules ovoid, ellipsoid,

                     or obovoid, widest above base; stems tufted; rhizome relatively thick and

                     lacking tubers, or rhizome absent.

                   20. Stamens 6; rhizome present.

                       21. Branches of inflorescence spreading at more than a 30 degree angle;

                             inflorescence less than twice as high as wide; sepals acuminate

                             ............................................................................................ J. articulatus 

                       21. Branches of inflorescence stiffly erect; inflorescence more than twice

                             as high as wide; sepals blunt, slightly longer than the petals

                             ................................................................................. J. alpinoarticulatus

                  20. Stamens usually 3, rarely 6 in species with long white tails on seed;

                        rhizome absent.    

                       22. Most heads with more than 8 flowers; mature capsules equalling

                             or slightly exceeding the perianth; stems often more than 70 cm tall.

                          23. Seeds 1.1-1.9 mm long, with pale tails at both ends; sepals shorter

                                than the petals ................................................................ J. canadensis   

                          23. Seeds 0.3-0.4 mm long, without pale tails; sepals at least as long as

                                the petals ...................................................................... J. acuminatus

                       22. Most heads with less than 8 flowers; mature capsules much exceeding

                             the perianth; stems less than 70 cm tall.

                          24. Sepals obtuse, 1.8-2.5 mm long, shorter than the petals, with wide

                                hyaline margins; inflorescence branches spreading

                                ..............................................................................  J. brachycephalus

                          24. Sepals acute, 2.3-3.1 mm long, about as long as the petals, with

                                narrow hyaline margins; inflorescence branches nearly erect

                                .................................................................................. J. brevicaudatus

 


         
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