256 PRACTIOAL BOTANY. 



lower pistillate ; perfect ones none. Spathe convolute, wavy 

 at the margins. Anthers 8-12, attached to the margin of a 

 shield-shaped, oblong connectile, and opening by a terminal 

 pore. Leaves arrow-shaped. Feltaudra Virginica, Raf. 



814. Flowers in a cylindric, club-shaped spike (that is, 

 on a spadix), sterile ones above, the fertile below (sometimes 

 separated by an interval, which is about 1 inch long). Each 

 stamen surrounded by 3 bristles. Fertile flowers : ovary 

 stalked ; stalk beset with long hairs ; style simple, long. In 

 marshes and ditches. Leaves sword-shaped. Typha. 



Flowers in spherical heads, the sterile above. 

 Stamens mixed with minute scales, irregularly interposed. 

 Ovaries ovoid, suiTounded by 3-6 scales, sessile. Stigma 

 oblique. Leaves linear, sheathing below. Borders of ponds. 



Sparganium. 

 813. L Sterile flowers with 1 stamen. Flowers axillary. 



Aquatics 816 



II. Sterile flowers with 2 or 3 stamens 819 



III. Sterile flowers with 4 or 5 stamens 828 



IV. Sterile flowers with more than 5 stamens. 

 Styles 1, 2, 3, or 4 sessile stigmas 837 



816. Leaves whorled, Imear, awl-shaped, 8-10. Flowers 

 (very often perfect), the upper sterile, the lower fertile. 



(545) Hippuris vulgaris, L. 



Leaves not whorled, but alternate, or opposite. 



Herbs submersed .817 



817. The naked flowers subtended by 2 small, opposite 

 bracts (supplying the wanting perianth), axillary, dichnous, 

 or perfect ; the sterile ones consisting of 1 stamen, the fer- 

 tile of 1, 2styled ovary. Fruit indehiscent, nut-like, 4-lobed 

 and 4-celled. Flowers expanding above the surface of the 

 water. (564) Callitriche. 



Flowers not subtended by two opposite bracts. 81 8 



818. Leaves thread-form, entire. Stamen 1 ; filament 

 filiform ; anther sagittate at the base. Fertile flower ; pistils 

 4 (2-5) in a cup-shaped involucre ; stigma peltate. 



(549) Zanichellia palustris, L. 



Leaves sparingly and very minutely repand-toothed 



(under a lens). Sterile flowers : stamen sessile, enclosed in a 



