Carex of San Mateo County and Santa Cruz Mountains Bioregion的日誌


Uncommon Carex characters in the bioregion


Hairy perigynia

Hairy foliage (sheaths, at least at mouth, or blades)

Leaves sometimes > 1 cm wide

Serpentine seeps

Dense tussocks among rocks in streambeds

Fruit usually aborted

Naturalized, garden escape

由使用者 rawlingstimby rawlingstimby2023年11月29日 20:00 所貼文


Where there's a sedge, there's often confusion -- Anon.

As mentioned in the Project summary, Carex is the largest genus in California where around 200 species occur, and one of the largest genera in the world with over 2,000 species. Due to the minor morphological differences between the species, it is often difficult to identify to species by sight. Source: CA Biologist's Handbook.

The inconclusiveness of identification by visual gestalt without examining inflorescence, spike, flower, and vegetative characters, which often involves dissection and micro-measurements, is especially significant and pertinent to observations of locally uncommon and/or look-alike sedges, typically members of the same subgroup with similar visual gestalts: for example C. bolanderi and C. leptpoda; C. subbracteata, C. harfordii, and C. pachystachys; C. nudata and S. senta, etc.).

C. subbracteata and C. pachystachys and other Broomsedges* illustrate these issues:

  • P. Zika (n.d.) California Carex checklist and synonymy: p. 74. "The shorter pistillate scales (never covering the perigynia), damper sites, shorter stems, more spreading perigynia, and often paler sheath summits may help separate C. pachystachya from C. subbracteata, but they need study."
  • J.T. Howell (1970) Marin Flora, 2 ed: p. 94 "In a large series of specimens, the differences between C. subbracteata and C. pachystachya Cham. become negligible . . ." (Several vouchers by Howell and Eastwood originally identified as C. subbracteata or C. harfordii deposited at UCJEPS and CAS have been annotated C. pachystachya by Reznicek and others in recent decades.)
  • Only herbarium voucher for C. pachystachya in Santa Cruz County: note the original label information by eminent Santa Cruz Mountains botanist Vesta Hesse and subsequent annotations by two experts.
  • The Jepson Manual, 2nd ed., p. 1317 on the Broomsedge group* (C. gracilior, C. harfordii, C. microptera, C. pachystachys, C. subbracteata, C. subfusca having vouchers and reports in our Bioregion): "For keying, use with subbasal perigynia in mature spikelets from first flush of growth; avoid perigynia from upper half of spike, they are always narrow and are not diagnostic; similarly basal-most perigynia are occ malformed; use ripe peri, immature peri gen do not show critical ventral veins".

  • Occasionally, iNat guide photos are atypical and consequently misleading -- [] -- for visual gestalt, as in the case of the common central coast and California Floristic Province endemic Carex harfordii; compare with records in this project. Accurate visual search image(s) is important, and needs to be combined with close examination of both inflorescence and vegetative characters.

    Indeed many iNat Carex records, including some of our own, tell one not much beyond this is a sedge growing in some or another area. Reports usually lack comments or photos documenting diagnostic characters, size of population, ecology. Taking a photo and relying on Computer Vision for identification does not work for most graminoids. When one suggests an identification, iNat prompts "Tell us why . . ." ; few answer. This prompt should also appear when making the original posting: Computer Vision, Uncertain, Recognized from previous determination, Keyed in a relevant flora, etc.

    A guide with macro-photos is Field Guide to the Sedges of the Pacific Northwest and California, 2nd ed., by Barbara L. Wilson, Richard E. Brainerd, Danna Lytjen, Bruce Newhouse, and Nick Otting of the Carex Working Group.
    Peter F. Zika, Andrew L. Hipp & Joy Mastrogiuseppe 2015, Carex, in Jepson Flora Project (eds.) Jepson eFlora, Revision 3, accessed on November 25, 2023.
    Peter W. Ball & A. A. Reznicek, Carex, in Flora of North America,, accessed on November 25, 2023.

    *Broomsedges, Section Ovales; 2 styles, spikes gynecandrous (pistillate above), perigynium winged, stems hollow.

    由使用者 rawlingstimby rawlingstimby2023年11月22日 17:16 所貼文