Georgian Court University

Recognizing Carex macrocephala

wpeF.jpg (61687 bytes)My students and I have recently discovered three populations of the Large Headed Sedge, Carex macrocephala, in New Jersey.  This represents a significant range expansion for this species which was previously native only to the coasts of the Northern Pacific. We suspect that the presence of this species in New Jersey has gone unnoticed for decades due to its being mistaken for the closely related Carex kobomugi.  Both have leaves with notable serration or serulatiwpeE.jpg (18682 bytes)on on the leaf edges. Both show paradioecy (male and female inflorescences on separate shoots, but both male and female shoots produced by an individual clone).  Even the basic appearance of the seed heads is similar.   However, as the common name (big headed or large headed sedge) suggests, the seed heads of C. macrocephala  are unusually large.  The seeds within them are darker in color and have very sharp, bidentate beaks. Features used to diagnose between the species include the angle of culm branching, the size of the proximal pistillate scales and the length of the anthers (See table below which is part of a paper submitted to the Bulletin of the Torrey Botanical Club reporting the finding of this species in New Jersey and some of the results of the research that we've carried out so far on the ecology of this species)

Diagnostic characteristics between the two species of Carex   within section Macrocephalae discussed in this study (adapted from Flora of North America 23.  Putative 2n number for C. kobomugi  obtained from a translation of www.jejunature.com)

Carex kobomugi

Carex macrocephala

Culms bluntly angled, generally smooth or slightly serrulate on 1 angle distally

Culms sharply angled, at least 1 angle serrulate distally

10-30cm tall

10-35cm tall

Pistillate inflorescences 2-4cm wide

Pistillate inflorescences 2.5-5cm

Proximal spikes appressed to ascending

Proximal spikes ascending spreading to spreading

Pistillate scales green or gold with distal margins white or pale gold

Pistillate scales reddish to brown with green or gold center, sometimes with distal margins white or pale gold

Pistillate scales 0.7-1mm wide, apex long- or short tapered with awn to 6-12mm

Pistillate scales 0.1-0.5mm wide, apex long- or short tapered with awn to 1.2-4mm

Anthers 4-6.5mm

Anthers 2.5-5mm

Perigynia appressed ascending to ascending with shallowly erose wing 0.4-0.6mm wide, base acute

Perigynia ascending to ascending-spreading sometimes spreading with deeply erose wing 0.7-1.7mm wide, base cordate

Beak +/- falcate 3-5mm from apex to achene, apex notched 0.4-0.6mm adaxially

Beak +/- straight 6.5-9mm from apex to achene, apex notched 0.7-1.5mm adaxially

Achenes 4-7 x 1.7-2.5mm

Achenes 3-4.5 x 2.3-3mm

2n = 88(?)

2n = 74, 78

Learn more about our discovery of Carex macrocephala in New Jersey

Click here to read our initial proposal for our study of the closely related species, C. kobomugi

Click here to see some pictures of us at work

Click here to read about last year's research plans.

Learn more about the Biology Department at Georgian Court University

Read more about what we've found out about the closely related species, Carex kobomugi , so far:
bulletWootton, LS. 2003.  Spread rate and changes in species diversity associated with the introduced Asiatic sand sedge, Carex kobomugi,   in New Jersey coastal dune communities.  5-page Extended Abstract.  Coastal Zone 2003 Conference Proceedings.
bulletMcGough A, Bevaart K, Ondreika J, Patel P, Wootton L.  2003.  Effectiveness of low-impact management strategies for eradication of Carex kobomugi (Asian sand sedge) from dune communities within New Jersey’s coastal parks.  5-page Extended Abstract. In Press for Coastal Zone 2003 Conference Proceedings.
bulletWootton, LS. 2002.  Chance Conversation Plants the Seed for NJ Sea Grant Research Project. The Jersey Shoreline.  Winter 2002. pp. 12-14.  (Reprinted in the Spring 2003 Court Pride as “Space Invaders: Hunting for Aliens on New Jersey’s Coastal Dunes")

 

Author: Louise Wootton. Ph.D.  Last updated January 15, 2006

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