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Carex

Collections of Carex should include basal portions of the stems and underground organs.  The basal portion of the plant is important for observing the morphology of the basal leaves (e.g., sheath color, presence/absence of blades, form of sheath upon disintegration). Underground organs are necessary to determine if a species is rhizomatous or cespitose (at the minimum, notes about a plant’s habit should be made on herbarium collections). Collections of Carex that lack mature spikes may not be able to be confidently determined. Some hybridization does occur, particularly within certain sections (e.g., Glareosae, Hymenochlaenae, Phacocystis, Vesicariae). Carex divulsa Stokes was reported from MA by Kartesz (1999), based on Hermann (1954), who reported C. virens Lam. The specimen was stated to be housed at US; however, searches of that museum have not been able to locate a voucher for this report. Carex laevigata Sm. (section Elatae) was thought to have been collected by Greene from Massachusetts near Boston in the early 1800s (Fernald 1911). It is unsure if the plant represents a mix-up in labeling (i.e., the origin was incorrectly thought to be United States) or if this species was truly collected in New England. In either case, no other collections have been reported, and the plant is not included in the following identification keys. Carex comosa ×C. lurida was reported from MA by Sorrie and Somers (1999). The voucher specimen is C. lurida— Fernald and Long 18155 ( MASS!). Reports of the hybrid Carex crinita ×C. scabrata from ma and nh were based on collections of C. gynandra (specimens at GH! and NEBC!). Reports of Carex ×‌sullivantii Boott were based on a specimen cultivated at the Cambridge Botanic Garden (specimen at NEBC!). Reports of Carex ×‌aestivaliformis Mackenzie from MA were based on a collection of C. aestivalis—3 Aug 1916, Churchill s.n. ( NEBC!).

See list of 19 species in 1a
Carex 1
1a. Spikes entirely staminate (i.e., no perigynia present)
See list of 195 species in 1b
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1b. At least some of the spikes partly or entirely carpellate
- See list of 16 species in 2a
  Carex 2
  2a. Spikes 1 per stem; rachilla often present in perigynium
- See list of 190 species in 2b
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  2b. Spikes normally 2 or more per stem (except depauperate individuals); rachilla absent from perigynium
  - See list of 98 species in 3a
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    3a. Stigmas 2; achenes lenticular to biconvex
    - See list of 67 species in 4a
      Carex 3
      4a. Spikes all similar and sessile, bearing staminate flowers at base or apex; bracteoles usually absent from the base of each spike
    - See list of 31 species in 4b
      Carex 4
      4b. Spikes dissimilar and some or all usually peduncled, with staminate flowers borne in separate or mixed spikes; bracteoles usually present at the base of each spike
  - See list of 106 species in 3b
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    3b. Stigmas 3; achenes trigonous to terete
    - See list of 32 species in 5a
      Carex 5
      5a. Perigynia pubescent or scabrous with hairs or scabrules several times longer than wide
    - See list of 100 species in 5b
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      5b. Perigynia glabrous (though long-papillose in some species)
      - See list of 74 species in 6a
        Carex 6
        6a. Bract of lowest carpellate spike consisting of a blade only, the sheath absent or extremely short, usually not exceeding 4 mm (or the bract absent altogether)
      - See list of 64 species in 6b
        Carex 7
        6b. Bract of lowest carpellate spike consisting of a blade and a prolonged, closed sheath, usually longer than 4 mm

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Show photos of: Each photo represents one species in this genus.