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.
Sedges and Rushes
Sedge culms are triangular and solid, with the leaves in three rows. Those of rushes are round and solid or pithy.
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.
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