MONOCOTYLEDONOUS OR ENDOGENOUS PLANTS. 531 



slightly keeled on the back. Shallow ponds. July. Float- 

 ing leaves 1-2' long; immersed leaves 4'-G' long. 



131. WATER-PLANTAIN FAMILY. Order, Alis^iaceje. 



Marsh herbs, usually with creeping runners or rootstocks, 

 nerved and reticulated sheathing leaves, and scape-like stems, 

 bearing the perfect or monoecious jioioers in spikes or 

 whorled racemes ; sepals and petals 3, or the latter some- 

 times wanting ; stamens few or numerous ; anthers 2-cell- 

 ed; ovaries 3 or many, with 1-2 anatropous or campylotro- 

 pous erect ovules; style short or none; acheniiim coria- 

 ceous, 1-2-seeded; embryo straight or curved, without 

 albumen. 



SYNOPSIS. 



Sub-order I. Juncagineae. Sepals and petals (when 

 present) greenish. Ovule anatropous. Embryo straight. 



Leaves rush-like. Flowers in spiked racemes Triglocuin. 



Sub-order II. Alismese. Petals white, deciduous. 

 Ovule campylotropous. Embryo curved or hooked. 



Flowers perfect. Achenia whorled. Racemes compound Alisma. 



clustered in a head Echinodorus. 



monoecious. Achenia clustered in a head Sagittaria. 



TRIGLOCHIN, L. 



Floioers perfect, in a spiked raceme; septals 3; petals 

 3, and greenish, like the sepals, or none; anthers 3-6, 

 nearly sessile, oval ; ovaries 3-6, united around a central 

 axis, from which they separate at maturity, 1-ovuled ; stig- 

 mas plumose; embryo straight; leaves rush-li'ke, fleshy, 

 2-ranked ; flow^ers small, bractless. 



T. triandrum, Michx. Leaves erect, linear-subulate, 

 semi-terete, dilated at the base and sheathing the base of 

 the terete scape ; flowers very numerous, on short pedicels ; 



