part_of part of part of portion of plant tissue non-vascular leaf costa 2011-04-29T02:30:17Z A portion of plant tissue (PO:0009007) that is a single or double strand in the center of a non-vascular leaf (PO:0025075) and has as part hydrome (PO:0030047) or leptome (PO:0030048). Found in bryophytes. Often contains both hydrome and leptome. Functions in support and conduction in a phyllid. The term costa is sometimes used for the midrib of monocot leaves, but this ontology class should only be used for non-vascular leaves. PO:0030072 PO_GIT:352 costa (Spanish, exact) costae (exact, plural) mid rib (broad) midrib (broad) non-vascular leaf midrib (exact) non-vascular leaf midvein (related) non-vascular leaflet midrib (related) phyllid costa (exact) phyllid midrib (exact) phyllid midvein (related) plant_anatomy rwalls 中肋 (Japanese, exact)