For the first year of its life, a seedling of this species has a normal-looking stem with opposite leaves. The next year, however, after its first dormancy, only a single leaf appears. As years go by, the plant will develop more leaves, all appearing directly from the tuber. Flowering is usually during the winter, in the period between time the previous growing season’s leaves drop and the next season’s leaves appear. The flowerstalks also emerge from the tuber.
Botanically, the base of the leaf is a stem. Leaf buds can be seen close to where the leaf sprouts from the tuber. For horticultural purposes, it is often useful to remove all but one of the leaves, in order to boost the size of the remaining leaf to dramatic proportions. If the removed leaves are taken with a bit of tuber attached to the base, they will often root and create a new tuber. This and sowing seeds are the most effective methods of propagation for this species.
Occasionally, a plant of Sinningia tuberosa will bear a resemblance to this species, if it has only a single leaf. The two species can be distinguished by the flowering pattern, by the conspicuous stem fragment at the base of a Sinningia tuberosa leaf, and by substantial differences in the tuber. Sinningia defoliata has a conventional “muffin” tuber, while S. tuberosa has a tuber with “fingers”.
Sinningia tuberosa is not in the same group as this species. However, S. helioana and S. sp. “Pancas” belong to the Corytholoma group along with S. defoliata, and they too have characteristic features of this species: a single leaf and flowering during the winter when any leaves have dropped. They can be distinguished from this species by the stem. S. defoliata has a fleshy, petiole-like segment at the base of the leaf, while the other two have wiry stems up to 10 cm [4 inches] long.
Another photo can be seen here.