The seeds and the rhizomes contain an abundance of starch, which renders them serviceable in some places for food.
Sudan is extracted partly from the roots of Landolphia or from the rhizomes of Landolphia Thollonii or Carpodinus lanceolatus.
It is obtained by breaking up the roots or rhizomes in hot water and separating the rubber, and machines have now been devised for this purpose.
The underground stems (rhizomes or tubers) are rich in starch; from that of Arum maculatum Portland arrowroot was formerly extensively prepared by pounding with water and then straining; the starch was deposited from the strained liquid.
Those with creeping rhizomes can be propagated by dividing these into well-rooted portions, and, if a number of crowns is formed, they can be divided at that season.
In most cases this can be performed with little risk, but the gleichenias, for example, must only be cut into large portions, as small divisions of the rhizomes are almost certain to die; in such cases, however, the points of the rhizomes can be led over and layered into small pots, several in succession, and allowed to remain unsevered from the parent plant until they become well-rooted.
Long creeping or subterranean rhizomes, with elongated internodes and sheathing scales; the widely-creeping, slender rhizomes in Marram-grass (Psamma), Agropyrum junceum, Ely7nus arenarius, and other sand-loving plants render them useful as sand-binders.