International Aroid Society
Dracontium Tubers

The tubers of Dracontium are typically depressed-globose or hemispheric, or often more or less rounded when young. The apex of the tuber is flat, with a few to many tubercles among many roots ( Fig. 1 ). The remainder of the tuber consists largely of a starch-storage organ ( Fig. 2 ). Since they are loosely attached, the tubercles often fall off and thus the tuber may appear to lack of tubercles. The starchy portion of the tuber is for the most part utilized during production of the inflorescence and new leaf, and is replenished during the growing season when the leaf blade is fully opened. The size, weight, and morphology of tubers vary from one season to the next. Starch accumulates in the tuber prior to inflorescence development, at which time the tuber enlarges to maximum size with its convex lower surface becoming fleshy, smooth, and whitish ( Fig. 3 ). During the development of the inflorescence and infructescence, often before or sometimes after new leaf development, starch is used to fuel new growth. During this time the tuber becomes smaller in size with its convex underside turning brownish and wrinkled ( Fig. 4 ). This diminution of the tuber is often associated with a change in depth rather than diameter of the tuber. Since the tuber becomes thicker or thinner at different seasons, there are often hollow spaces both above and below the tuber. The hollow space under the tuber may be 3-8 cm or more high, while that above the tuber is often 1-3 cm high. The upper space allows tubercles and contractile roots to grow, while the lower one allows the tuber itself to sink deeper into the soil when the contractile roots dry out during dormancy. Since most plants usually start out near the surface either from seeds or tubercles, this mechanism is necessary to enable the tuber to enlarg and to assume a deeper position and, thus gain protection from corm-eating herbivores such as agoutis and wild pigs. On the other hand, these same animals are responsible for distributing the tubercles.