They also contain small adaxial resin vesicles. These cells are present on the adaxial or the upper surface of the leaf. The sepals have bristles on the adaxial surface. Sparse stellate hairs persist on the adaxial surface. In the angle (adaxial) between the leaf and the stem, is the axil. They are also flat, linear and have an adaxial bottom which is hispid and tipped. Sporangia are borne in the axil or on the adaxial surface of the sporophyll. A single wing ran down the adaxial side of each pitcher. "Pelargonium" has only one nectary gland on the adaxial side of the flower. The costa are long, sometimes excurrent, and lack an adaxial pad of cells. The petioles are short and stout, with a prominent adaxial groove. Ovules are produced on the adaxial surface of the cone scales. On the adaxial surface, leaves are dark green with deeply impressed veins. Proteins of the "HD-ZIPIII" family have been implicated in defining the adaxial identity. The laminar adaxial surface is covered in insect-trapping glands.