bb) Characters not as above; if aquatic plants then usually with well- developed leaves: c) Ovary apocarpous, of more than 1 carpel: d) Submerged aquatic plants: e) Perianth-segments 1-3, white or coloured. =Aponogetonaceæ= ee) Perianth-segments 4 and herbaceous, or absent. =Potamogetonaceæ= dd) Not aquatic or if so then not submerged: e) Carpels indehiscent; ovules 1 to few, basal or on the inner angle of the carpel; marsh or aquatic herbs. =Alismataceæ= ee) Carpels dehiscent; ovules numerous on reticulately branched parietal placentas; scapigerous marsh herbs with milky juice; stamens usually 9. =Butomaceæ= eee) Carpels or fruit indehiscent, trees or shrubs with simple stems and usually large, often palmate leaves. =Palmaceæ= (part) cc) Ovary syncarpous or carpel solitary: d) Ovary superior: e) Flowers in the axils of membranous or more or less dry bracts (glumes) arranged in spikelets mostly arranged in spikes, racemes, panicles or heads; carpel solitary; perianth of small scales or bristles or absent: f) Stems usually triangular, solid and without nodes; leaf-sheaths mostly closed all round the stem and usually without a ligule; filament often attached to the base of the anther; ovule basal; seed free from the pericarp. =Cyperaceæ= ff) Stems mostly cylindrical and hollow between the nodes; leaf- sheaths nearly always split down one side and often terminating in a distinct ligule; filament usually attached to the back of the anther; ovule attached laterally; seed more or less adnate to the pericarp. =Gramineæ= ee) Flowers usually with a distinct perianth or at any rate not in spikelets, etc., as above; ovary usually composed of more than 1 carpel: f) Flowers mostly hermaphrodite or if unisexual then not collected into involucrate heads or dense spikes: g) Ovules on parietal placentas; fertile stamens 3: all the perianth-segments petaloid; aquatic herbs; stamens 3 or 1. =Pontederiaceæ= (part) gg) Ovules on axile or basal placentas; fertile stamens usually 6: h) Perianth present: i) Perianth-segments 2-seriate, the outer herbaceous, the inner petaloid; leaf-bases sheathing. =Commelinaceæ= ii) Perianth-segments all more or less petaloid: