168 



BOTANY. 



in Vallisneriaj and are borne on long stalks, by means of which 

 they reach the surface of the water, where they expand and 

 are ready for pollination. The male flowers (Fig. 91, J, K} 

 are extremely small and borne, many together, surrounded 

 by a membranous envelope, the whole inflorescence attached 



FIG. 91. Types of Helobise. A, inflorescence of arrow-head (Sagittaria), 

 with a single female flower, x % (Alismacese). B, section through the 

 gynoecium, showing the numerous single carpels, x 3. C, a ripe fruit, x 3. 

 I), a male flower, x i. E, a single stamen, x 3. F, a leaf of Sagittaria 

 variabilis, x v 6 . G, ditch-moss (Elodea), with a female flower (fl.), x %. 

 (Hydrocharidese). H, the flower, x 2. an. the rudimentary stamens, st. the 

 stigma. /, cross-section of the ovary, x 4. J, male inflorescence of eel-grass 

 (Vallisneria} , x l. K, a single expanded male flower, x 12. st. the stamen. 

 i, a female flower, x 1. gy. the stigma. 



by a short stalk. When the flowers are ready to open, they 

 break away from their attachment, and the envelope opens, 

 allowing them to escape, and they immediately rise to the 

 surface where they expand and collect in great numbers about 

 the open female flowers. Sometimes these are so abundant 



