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Culm
culm [ kuhlm ] noun: the stem of grasses, sedges, rushes, and cattails
Culms is the term used to describe the stems of the monocotyledonous plants called graminoids, as in Poaceae (grasses), Cyperaceae (sedges), Juncaceae (rushes), and Typhaceae (cattails).
The culms of grasses have nodes (joints), which are somewhat swollen, and internodes. The leaves emerge from the nodes, with the sheath on one side of the culm and the blade on the other, wrapping it so tightly the culm is unseen at that point. The culms are usually hollow between the nodes, are unbranched, and usually end in an inflorescence.
Left to right: pandas with bamboo (Tian Tian and Bei Bei), culm cross-section, grass structures, Chasmanthium latifolium (leaf and culms with inflorescence).
Sedge culms are triangular and solid, with the leaves in three rows. Those of rushes are round and solid or pithy.
Left to right: Carex blanda, Carex glaucescens, Carex muskingumensis 'Oehme,' Juncus effusus, Juncus inflexus 'Blue Arrows.'
Cattails
Cattail culms are also round, leaves emerging from the culm or plant base, and with male and female flowers on the same culm. The larger female inflorescences are below the smaller male flowers near the end of the stem. These velvety heads turn into wind-borne fluff as the seeds ripen. Cattails grow in wet places almost all over the world. While they can be invasive, they also have ethnobotanical uses by indigenous people and are used in silage, paper-making, and for other purposes.
Left to right: Tyhpha latifolia at Meadowlark Botanical Gardens, Typha app. at The Mount Vernon Trail swamp (close-up and en masse).
Bedish JW. 1964. Studies of the germination and growth of cattail in relation to marsh management. Iowa State University, Digital Repository:
https://dr.lib.iastate.edu/entities/publication/40a81f3a-ade4-4bfb-b064-33448974ee7a
Grass Structures. Forage Information System, Oregon State University Department of Crop and Soil Science. (https://forages.oregonstate.edu/regrowth/how-does-grass-grow/grass-structures, accessed October 23, 2021).
Grasses, Sedges, Rushes. Ecological Atlas of Denali's Flora. Denali National Park and Reserve.(https://ecologicalatlas.uaf.edu/index.php/browse-plant-species/atlas-group/?nps_gf=4&nps_num=1&overview=1, accessed October 23, 2021).
Illinois Wildflowers, © 2002-2020 by John Hilty. (http://www.illinoiswildflowers.info/index.htm accessed October 23, 2021).
Lab 8. Monocots, Commelinids: Poales (Poaceae, Cyperaceae, Juncaceae, Typhaceae); Arecales (Arecaceae). Department of Plant Sciences. University of California, Davis.
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