It may be in the form of bulb, corm, or rhizome.
"Ontario Teachers' Manuals: Nature Study"
Ontario Ministry of Education
The Ard-Ri, corm of the Hundred Battles, had taken his place on the raised dais which commanded the whole of that vast hall.
"Irish Fairy Tales"
James Stephens
Leaves: All from an egg-shaped corm; mostly longer than scapes, slender, grass-like, more or less hairy.
"Wild Flowers Worth Knowing"
Neltje Blanchan et al