The rhizome of Imperata cylindrica (Japanese Blood Grass)

I was transplanting some Imperata cylindrica from one container to another, and as always I stopped to look at its rhizomes.

Rhizomes are underground stems, and the green form Cogon grass forms extensive networks that may comprise up to 60% of the total mass of the plant! This very low shoot to rhizome/root ratio means that damage to the above ground shoots through fire or cutting does not kill the plant.

The rhizomes also allow colonies to quickly expand, with new stems and roots developing in the nodes of the rapidly spreading rhizomes. I am always fascinated to see new culms popping out of the ground far from the main clump of I. cylindrica.

The sharp tipped rhizomes have also been implicated in stabbing surrounding structures, whether the rhizomes or roots of competing plants, or its own underground rhizomes. The ability of the rhizomes to do this is because the tip of the rhizome is surrounded by continuously growing leafy bracts that have amazingly sharp tips. The tips can draw blood when touched too hard, and they allow the rhizomes to burrow through hard ground and even break through plastic tarp covering the soil!

References:

Characteristics of Cogon Grass Rhizomes and its Perforation of a Maiden Cane Rhizome.
Muchovej, J. J.; Onokpise, O. U.; Bambo, S. K. // International Journal of Botany; 2009, Vol. 5 Issue 4, p314