Order NAIADALES 
By JoHN KUNKEL SMALL 
Aquatic or marsh-inhabiting caulescent or acaulescent herbs with short or 
elongate rootstocks. Leaves alternate or opposite, flat or terete above the 
stipular base; blades present, narrow or broad, usually entire, rarely toothed 
or wanting, the phyllodia various in shape. Flowers perfect or unisexual and 
the pistillate ones rarely dimorphous, solitary or clustered in the leaf-axils, or 
spirally arranged in a spike or borne on a one-sided spadix. Perianth single 
or double, but imperfect, or obsolete or wanting. Androecium of 1-4 stamens; 
filaments very short or obsolete ; anthers mostly 2-4-celled, usually with large, 
sometimes petaloid connectives. Gynoecium of a single carpel or of 2-several 
distinct or united carpels; ovary superior; style present or wanting; stigma 
disk-like, cup-like or elongate. Fruit.drupelets or nutlets, or utricular. 
Plants either monoecious or dioecious, the staminate or the pistillate flowers of one kind, or with 
perfect flowers; leaf-blades commonly flat above the stipular sheath. 
Gynoecium of distinct carpels. Fam. 1. ZANNICHELLIACEAE. 
Gynoecium of one carpel or of united carpels. 
Staminate and pistillate flowers borne alternately on a one- 
sided spadix, laterally attached. Fam, 2, ZOSTERACEAE. 
Staminate and pistillate flowers borne in the leaf-axils. 
Staminate flowers consisting of 2 anthers terminating an 
elongate pedicel; perianth wanting; stigmas filiform ; 
acaulescent plants with entire leaf-blades. Fam. 3. CyMODOCEACEAE, 
Staminate flowers sessile or nearly so, consisting of an 
anther surrounded by the perianth; stigmas subulate; 
caulescent plants with spiny-toothed leaf-blades. Fam. 4. NAIADACEAE. 
Plants with perfect, staminate and pistillate flowers borne in long- 
peduncled spikes and also pistillate flowers borne singly in the 
leaf-axils at the base of the plant; leaves terete above the stipular 
sheath. Fam, 5. LILAEACEAE. 
VoLuME 17, Part 1, 1909] 11 
