The central capsule of the Pylodiscida is constantly flat, discoidal, and enclosed between the two sieve-plates of the surface.
|sieve cell |
An elongated, food-conducting cell in phloem characteristic of gymnosperms. Sieve cells have pores through which nutrients flow from cell to cell, but they have no sieve plates like the more specialized sieve-tube elements of angiosperms. Compare sieve-tube element.