PHANEROGAMIA 



483 



Fig. 426. — Sagittaria sagittifolia. a, Flower; &, fruit 

 after removal of part of the carpels. (Magnified.) 



water. As representative species may be mentioned Alisma Plantago, Water 

 Plantain, Sagittaria sagittifolia, Arrow-head, and Sutomus umbellatus, Flowering 

 Rush. 



The small family Juncaginaeeae may be distinguished from the preceding by 

 its grass-like habit and calycoid 

 perigone. It probably represents 

 the oldest group of the order. Tri- 



glochin palustris, Arrow-Grass, is /^ >, \^^^^ W w-C£2^ 



a familiar example of this family. 



Family Hydrocharitaeeae. 



— Flowers epigynous, usually 

 UNISEXUAL; perianth consist- 

 ing of both CALYX and 

 COROLLA, or the latter may be 

 suppressed ; stamens three to 

 many ; ovary of three or 

 more carpels. Fruit with 

 irregular dehiscence, commonly many-seeded. 



The Hydrocharitaeeae are water-plants occurring in fresh water in all zones, and 

 in the tropical seas. They are usually submerged, or at the most projecting their 

 inflorescences above the water, rarely freely floating on its surface. The German 

 Flora possesses only two native species — Sydrocharis morsus ranae, Frog's-Bit, 

 floating on the surface of ponds, with roundly cordate leaves, and Stratiotes aloides, 



Water-Soldier, whose sword- 

 shaped, spiny leaves, to- 

 gether with the female in- 

 florescences, appear above the 

 surface of the water only to 

 become again submerged 

 after fertilisation. Elodea 

 canadensis, the widely distri- 

 buted Water-Pest introduced 

 into Europe from North 

 America about fifty years 

 ago, is represented only by 

 female plants. 



Family Potamogeto- 

 naeeae. — Flowers hypo- 

 gynous, unisexual, or 

 hermaphrodite, usually 



NAKED or with REDUCED, 

 CALYCOID PERIGONE ; 



androecium and the 



apocarpous gyncecium 



Eipe carpels drupaceous, one-seeded (Fig. 



Fig. 427. — Potanwgeton natans. 1, Apex of flowering shoot ; 

 2, flower viewed from above ; 3, flower viewed from the side ; 

 4, diagram of flower. (After Wossidlo.) 



ONE- TO FOUR-MEROUS. 

 427). 



Onjaccount of the great reduction and simple structure exhibited by the flowers 



