phyllocladium

from The Century Dictionary.

• noun In botany, a stem or branch which assumes the functions of foliage. The broad, succulent stems of the Cactaceæ are familiar examples.
• noun A granular or scale-like body which occurs on the podetia of certain lichens, especially Stereocaulon.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A flattened stem or branch which more or less resembles a leaf, and performs the function of a leaf as regards respiration and assimilation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany A flattened stem or branch that more or less resembles a leaf, and performs the function of a leaf as regards respiration and assimilation.