[Vol. 1 



120 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



alternate ; leaves of mature sporophyte alternate, and usually 

 parallel- veined ; fibro-vascular bundles of the stem scattered, 

 usually not arranged in rings. (Species about 23,700.) 



Sub-Class ALTERNIFOLIAE-STROBILOIDEAE. Axis 

 of the flower from spheroidal to flattened, bearing on its sur- 

 face the hypogynous perianth and stamens (or the stamens 

 may be attached to the perianth), and the many or few, su- 

 perior, separate or united carpels. 



Order Alismatales. Carpels separate, superior to all other 

 parts of the flower; endosperm scanty or none (species about 

 409). Related to and probably derived from the Ranales of 

 the dicotyledons. 



Family 1. Alismataceae. Water Plantains. Aquatic or 



paludose herbs with mostly radical, often large leaves; flowers 

 small to large; perianth in two whorls of three leaves each 

 (calyx and corolla); placenta sutural; ovules mostly solitary. 

 Alisma, Sagittaria. (Pf. 2 1 : 227.) 1 



Family 2. Butomaceae. Aquatic or paludose herbs, bear- 

 ing narrow or broad leaves, with convergent veins; flowers 

 large; perianth in two whorls, of three leaves each (calyx and 

 corolla); placenta parietal; ovules many. Butomus, Lim- 

 nocharis. (Pf. 2 1 : 232.) 



Family 3. Triuridaceae. Very small, pale, leafless plants 

 growing in wet places in tropical countries. Triuris. (Pf. 2 l : 

 235.) 



Family 4. Scheuchzeriaceae. Aquatic or paludose herbs 

 with rush-like leaves, and small flowers, with a two-whorlrd 

 perianth, each 4— 6-parted. Triglochin, Scheuchzeria. (Pf. 



2 1 :222.) 



Family 5. Typhaceae. Cat-tails. Aquatic or paludose 

 herbs, with linear, sheathing leaves and cylindrical-crowded 

 flowers; pistil 1-celled; ovule 1. Typha. (Pf. 2 1 : 183.) 



Family 6. Sparganiaceae. Aquatic or paludose plants 



with creeping rootstocks and erect stems, bearing linear 



1 The abbreviation "Pf." lias reference to Engler and Prantl'a 'Naturlichen 

 Pflanzonfamilien,' and the bold face, exponent, and Roman figures following refer 

 respectively to "Abteilung," "Teil," and page of this publication. 



