ENDOGEN^E FLORIDA. 



185 



176. Alismacete. Floating or swamp plants. Sepals 3, 

 herbaceous, inferior. Petals 3, petaloid. Stamens definite or 

 indefinite. Ovaries several, 1-celled. Ovules ascending. Fruit 

 not opening, 1- or 2-seeded. Embryo doubled upon itself. 



USES. The leaves are acrid. The rhizoma of the Arrow- 

 head, Sagittaria, is eatable. 



TYPICAL GENERA. Alisma, Sagittaria. 



1. Leaf of Ouvirandra fenestralis. 2. A flower cut open. 3. Section of a ripe 

 carpel of O. Bernieriana. 4, 5. Embryo in different positions : the thicker part is 

 the cotyledon, the smaller the plnmula. 



177. Acoracea. Rhizoma jointed. Leaves ensiform. Flow- 

 ers hermaphrodite, surrounded with inferior scales. Spathe 

 leaf-like. Stamens with 2-celled anthers, turned inwards. 

 Ovaries distinct. Fruit finally juiceless. Seeds albuminous. 

 Embryo with a cleft on one side. 



USES. Acorus Calamus was the sweet rush with which the 

 rooms of the higher orders were strewed before the intro- 

 duction of carpets, &c. It has a fragrant rhizoma, whose 

 aromatic qualities have rendered it useful in medicine : it is, 

 however, chiefly employed as an ingredient in hair-powders. 



TYPICAL GENUS. Acorus. 



178. Naiadaceee or Flumales. Water-plants. Leaves 

 very cellular. Flowers inconspicuous, hermaphrodite or uni- 

 sexual. Perianth of 2 or 4 pieces, rarely wanting. Stamens 

 definite. Ovaries 1 or more, superior ; ovule pendulous. 

 Fruit not opening, 1-celled, 1-seeded. Albumen none ; em- 

 bryo antitropous, with a lateral cleft. 



