ARTIFICIAL KEY TO THE FAMILIES. Ixiii 



or tubular ; inflorescence rarely spadix-like and then 

 in herbs with leafy submerged floating stems ; ovary 

 sessile, of 1-several free carpels ; fruit of follicles 

 or an achene ; or if drupaceous, then of 2 or 

 more free carpels ; marine or fresh-water erect or 

 floating herbs : 



Flowers in racemes or spikes ; or if axillary, then 

 the ovule solitary and pendulous ; ovary of 2-9 free 

 carpels ; fruit of follicles or drupelets : 



Ovules 2-8 ; basal or 2-seriate on the ventral 

 suture, ascending ; perianth of 1-3 white or 

 coloured segments ; stamens 6 in 2 whorls ; fruit 

 of 3 inflated, beaked follicles 



CLXXI. APONOGETONACEAE. 

 Ovule 1, apical or parietal, pendulous ; perianth 

 0, or of 3-4 green segments, rarely cupular ; 

 anthers 1-4, sessile ; fruit of 2-9 drupelets 



CLXXII. POTAMOGETONACEAE. 



Flowers axillary, solitary or clustered ; ovary of 

 1 carpel ; ovule 1, basal, erect ; perianth tubular, 

 herbaceous or hyaline, or in $ ; anther 1, adnate 

 to the perianth ; fruit an achene 



CLXXIII. NAJADACEAE. 



Inflorescence of heads or spikelets composed of solitary 

 flowers in the axils of glumaceous bracts ; perianth 

 segments small, bristle- or scale-like or ; seeds albu- 

 minous : 



Flowers in depressed or subglobose, usually androgynous 

 heads, always 1-sexual ; ovary 3- or 2-celled ; ovule 1 in 

 each cell, pendulous ; perianth segments 6 or fewer, 

 usually in 2 series, membranous, scarious or hyaline, free 

 or connate ; usually aquatic or marsh, scapigerous herbs 



CLXXIV. ERIOCAULACEAE. 



Flowers in spikelets with imbricating glumes, 1- or 2-sexual, 

 rarely dioecious ; ovary 1 -celled ; ovule 1, erect or 

 ascending ; perianth or of bristles or scales ; grassy 

 herbs, shrubs or trees : 



Stems solid ; leaves 3-ranked, rarely ; sheaths rarely 

 with a ligule, closed in front ; perianth or of bristles 

 or scales ; fruit a compressed or 3-angled nut with the 

 seed free within ; embryo inside the albumen ; sedges 



CLXXV. CYPEBACEAE. 



