402 FROGBIT FAMILY. 



Subclass II. MONOCOTYLEDONS (or Endogens). 



Distinguished by having the woody matter of the stem in 

 distinct bCuidles scattered without obvious order through- 

 out its whole breadth, never so arranged as all to come in 

 a circle; when abundant enough to form proper wood, as 

 in Palms and the like, this is hardest and the bundles most 

 crowded toward the circumference. Embryo with a sin- 

 gle cotyledon; the first leaves in germination alternate. 

 Leaves mostly, but not always, parallel-veined. Parts of 

 the flower almost always in threes, never in fives. See 

 Lessons, p. 138, and for style of vegetation, p. 26, Fig. 71. 



The plants of this class may be arranged under three 

 generally well-marked divisions. 



I. Petaloideous Division. 



Flowers with a perianth (calyx and corolla) which is 

 usually (except in Rush-like plants) colored, not on a 

 spadix. 



CXI. HYDROCHARIDACE^, FROGBIT FAMILY. 



Water plants, with dicecious, monoecious, or polygamous 

 flowers on scape-like peduncles from a sort of spathe of one 

 or two leaves, or sessile, the periantli in the fertile flowers of 

 6 parts united below into a tube which is coherent with the 

 surface of a compound ovary ; stamens 3-12, sometimes mono- 

 delphous ; stigmas 3 or 6. Fruit ripening under water. 



« Growing under water, the fertile flowers only rising to the surface ; the sterile (not 

 often detected) breaking off their short stalks, and floating on the surface around 

 the pistillate flowers. 



1. ELODEA. Stems leafy and branching. Fertile flowers rising from a tubular spathe; 



the perianth prolonged into an exceedingly slender stalk-like tube, 6-lobed at top, 

 commonly bearing 3-9 apparently good stamens ; ovary 1-celled with a few ovules on 

 the walls ; style coherent with the tube of the perianth ; stigmas 3, notched. 



2. VALLISNERIA. Stemless ; leaves all ia tufts from creeping rootstocks. Fertile 



flowers with a tubular spathe, raised to the surface of the water on an extremely long 

 and slender scape ; tube of the perianth not prolonged beyond the 1-celled ovary, with 

 3 obovate outer lobes (sepals) and 3 small inner linear ones (petals), and no stamens. 

 Ovules very numerous, lining the walls. Stigmas 3, sessile, 2-lobed. Fruit cylindrical, 

 berry-like. 



