TYPHACE^E 165 



2. TYPHA, L. 



Spikes very dense, brown, cylindrical, with deciduous 

 leafy bracts ; stamens several ; monadelphous ; ovaries 

 stalked, often imperfect. 



T. latifolia^ L., Greater Reed-Mace (often called Bul- 

 rush); stem 3-6 ft., spikes 6-12 in. long, i in. diameter; 

 ditches and ponds, frequent. T. angustifolia, L., Smaller 

 Reed-Mace ; leaves narrower, spike J-f in. diameter, not 

 continuous; not so common. T. minima, Hfn. (Lax- 

 manni, Lep.); stem 1-3 ft., stem-leaves very small, 

 scale-like; water-sides, occasional. T. Shuttleworthii, 

 Koch; inflorescence composed of two contiguous grey 

 spikes; Switzerland, Dauphiny, occasional. 



Order XCIIL NAIADE^E. 



Flowers unisexual or bisexual, inconspicuous ; perianth 

 o or 3~4-lobed, inferior; ovary of 1-4 carpels, with one 

 seed in each carpel. Aquatic or marsh plants, usually 

 with floating leaves sheathing at the base. 



I. POTAMOGETON, L. 



Flowers bisexual, in axillary or terminal spikes; peri- 

 anth-segments 4, green; stamens 4; carpels usually 4; 

 leaves submerged and translucent, or floating and opaque, 

 often with connate stipules. 



No species of Pond-Weed are truly alpine, though some 

 are found at considerable altitudes. The species are often 

 difficult to distinguish, and require more minute descrip- 

 tions than can be given here. The following are given 



