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Pests > Pests Entities > Weeds > Sedge, Pohnpei, FSM

Pests Pests Entities Weeds Sedge, Pohnpei, FSM

Sedge, Pohnpei, FSM

December 2013. Photos of a sedge found in Pohnpei, Federated States of Micronesia. What is it? it looks like nutsedge but there are no bulbs, and it is more upright.

A member said it is not nutgrass: There are two species of sedges which are commonly known as “nutgrass.” Both are in the genus Cyperus. Purple nutsedge, Cyperus rotundus is common all over the Pacific Islands region. It is not very shade tolerant, so it is not a problem in traditional agroforestry production systems, but when people switch to row crops, it can get so bad that people actually abandon their farms. Purple nutsedge produces chains of tubers underground, and these can survive all sorts of control methods. It generally does not grow more than about 20 cm tall, but it can grow taller.

The other species of nutsedge found in the Pacific is Cyperus esculentus, or yellow nutsedge. It is more of a cold-weather plant, and it is a big problem in some places in the US. In the Pacific Islands, it is a problem on the big island of Hawaii, but whether it is found elsewhere in the Pacific the writer was not aware. Yellow nutsedge also produces tubers, but not in chains like purple nutsedge.

This is from Barbara Waterhouse, DAFF, Australia, who kindly sent a note about Konrad’s sedge specifically, and the identification of sedges generally.

“I did see Konrad’s request come through but while agreeing with Joel and Warea that it isn’t Cyperus rotundusI didn’t feel comfortable suggesting any names. I find sedges difficult to identify, even when they are right in front of me and under the microscope. Photographs are generally not adequate for sedge identification because apart from needing to know gross morphological characters like whether there are nutlets, rhizomes, stolons or fibrous roots, another character that helps separate them is whether the style is bifid or trifid. This can also be inferred from the shape of mature seeds.

After all this time, I still get excited if I get a sedge ID right when I send specimens off for herbarium verification, hence my utmost caution with images. Sorry that I can’t help this time, but I am happy if you want to circulate any of my comments above. The best advice would be for a specimen to be sent to a regional herbarium for ID”.