472 ALISMACE.E. ( WATER-PLANTAIN FAMILY.) 



ORDER 141. ALISMACE^E. (WATER-PLANTAIN FAMILY.) 



Marsh herbs, usually with creeping runners or rootstocks, nerved 

 and reticulated sheathing leaves, and scape-like steins, bearing the 

 perfect or monoecious flowers in spikes or whorled racemes. Sepals 

 and petals 3, or the latter sometimes wanting. Stamens few or nu- 

 merous: anthers 2-celled. Ovaries 3 or many, with 1-2 anatropous 

 or campylotropous erect ovules. Style short or none. Achenium co- 

 riaceous, 1 - 2-seeded. Embryo straight or curved, without albumen. 



Synopsis. 



SUBORDER I. JUNCAGINE^E. Sepals arid petals (when present) green- 

 ish. Ovule anatropous. Embryo straight. 



1. TRIGLOCHIN. Leaves rush-like. Flowers in spiked racemes. 



SmoRDEU II. ALISME^E. Petals white, deciduous. Ovule campylo- 

 tropous. Embryo curved or hooked. 



2. ALISMA. Flowers perfect. Achenia whorled. Racemes compound. 



3. ECHINODORUS. Flowers perfect. Achenia clustered in a head. 



4. SAGITTARIA. Flowers monoecious. Achenia clustered in a head. 



1. TRIQLOCHIN, L. 



Flowers perfect, in a spiked raceme. Sepals 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. 

 Stigmas plumose. Embryo straight. Leaves rush-like, fleshy, 2-rauked. 

 Flowers small, bractless. 



1. T. triandra, Michx. Leaves erect, linear-subulate, semi-terete, di- 

 lated at the base and sheathing the base of the terete scape ; flowers numerous, 

 on short pedicels ; sepals oval, deciduous; petals none ; anthers and ovaries 3 ; 

 fruit globose-triangular, pointless, when dry 3-winged by the compressed 3- 

 ribbed achenia ; embryo oblong. Salt marshes along the coast. August - 

 Sept. Scape and leaves - 1 high. 



2. ALISMA, L. WATER-PLANTAIN. 



Flowers perfect in a whorled panicle. Sepals 3. Petals 3, involute in the 

 bud, deciduous. Stamens 6 -12. Ovaries numerous in a simple whorl. Style 

 short. Achenium 1-seeded, 2 -3-keeled on the back. Roots fibrous. Leaves 

 mostly oval or cordate, nerved, shorter than the scape. Flowers white. 



1. A. PlantagO, L. Leaves long-petioled, ovate or oblong,- acute, 

 rounded or cordate at the base, 3-9-nerved; panicle large, lax, the whorled 

 branches and elongated filiform pedicels bracted at the base ; achenia obtuse, 

 15-20 in a whorl. Ditches and margins of ponds in the upper districts 

 July - August. Leaves 2' - 4' long. Panicle 1 - 2 long. 



