vaginula

from The Century Dictionary.

• noun In botany, a diminutive vagina or sheath; specifically, in mosses, the sheath round the base of the seta where it springs from the stem. Also vaginule.
• noun In zoology, a little sheath; a small vagina.

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

• noun A little sheath, as that about the base of the pedicel of most mosses.
• noun One of the tubular florets in composite flowers.

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

• noun botany A little sheath, such as that about the base of the pedicel of most mosses.
• noun botany One of the tubular florets in composite flowers.