Recognizing Carex macrocephala
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 serulati
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
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:
 | Wootton, LS. 2003. Spread rate and changes in
species diversity associated with the introduced Asiatic sand sedge, Carex kobomugi,
in |
| McGough 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 |
| Wootton, LS. 2002. Chance Conversation Plants the Seed for NJ Sea Grant Research
Project. The |
Author: Louise Wootton. Ph.D. Last updated January 15, 2006