ARUM FAMILY. 457 



II. Spadiceous Division. 



Flowers either naked, i.e. destitute of calyx and corolla, 

 or these, if present, not brightly colored, collected in the 

 sort of spike called a spadix, which is embraced or sub- 

 tended by the kind of developing bract termed a spathe. 

 The most familiar examples of this division are offered by 

 the Arum Family. There are various exceptions to this 

 style of inflorescence, and the division, like all others, is 

 merely artificial, but it will serve to aid the beginner. 

 The first two families are too difficult for the beginner. 



CXXVII. NAIADACEiE, PONDWEED FAMILY. 



Marsh or aquatic plants with steins mostly leafy and jointed, 

 the leaves stipulate or sheathing, the flowers (sometimes not 

 spathaceous) perfect or unisexual, with 4 or 6 distinct incon- 

 spicuous segments, or the perianth tubular, or even wanting. 

 Stamens 1-6. Ovaries 1-6, distinct or nearly so, 1-celled and 

 usually 1-ovuled, the fruit follicular or fleshy. Our genera are 

 Tkiglochin, Scheuchzeria, with bladeless leaves, allied to 

 the water Plantain Family, the former with naked, scape-like 

 stems ; and Potamogeton, the Pondweeds, with many diffi- 

 cult species, Euppia and Zostera, grass-like immersed plants 

 on the seacoast, Zannichellia, a similar plant in fresh water, 

 and Naias, slender and inconspicuous branchy plants, mostly 

 in fresh water. 



CXXVIII. LEMNACEiE, DUCKWEED FAMILY. 



Minute, stemless plants reduced to a floating leaf-like body 

 three fourths inch or less long (in Lemna) or even to minute, 

 green grains (in Wolffia). The least of flowering plants. 



CXXIX. ARACEiE, AHUM FA^MILY. 



Perennial herbs with pungent or acrid watery juice, leaves 

 often with veins reticulated so as to resemble those of Dicot}-- 

 ledons, small perfect or imperfect flowers in a fleshy head or 

 spike called a spadix, usually furnished with the colored or 

 peculiar enveloping bract called a spathe. Floral envelopes 



