76. ORCHIDACE^E. 159 



ORD. 85. LEMNACE.E. 



1. LEMNA. Spatha membranous, nrceolate. St. 1 2, distinct, 

 Anthers 2-celled, didymous. Ovary 1 -celled. 



ORD. 86. NAIADACLE. 



1. POTAMOGETON. Flowers perfect. Perianth of 4 scale-like 

 segments. St. 4. Anthers sessile. Ovaries 4. Stigmas 



2. ZANNICHELLIA, Flowers monoecious, axillary. St. 1, filament 



long. Perianth none. Fertile flower. Perianth of 1 scale. 

 Ovulus 4, Stigma peltate. 



3. ZOSTEHA. Stamens and pistils arranged in 2 rows upon one 



side of a spadix. Spatha sheathing. Anther 1. Ovary 1. 

 Stigmas 2. Growing in the sea. 



SPECIES OF PETALOIDE/E. 

 75.-HYDROCHARIDACE^I. 



1. ANACHARIS. Anacharis. 



*A. ALSINASTRUM, Bab. Long-Flowered Anacharis. Stems 

 entirely under water, 1 2 ft. long. Le. 3 4 in a whorl, oval- 

 oblong, blunt, minutely serrulate. Female fl. sessile in the upper 

 axil of the le. Spatha tubular, 2-lobed. Peri, slender, 2 3 in. 

 long. Male fl. not known in this country. 



Frequent. In ponds, overrunning many of the streams, and now becoming a 

 pest in canals. Supposed to be introduced from America, but how remains 

 unknown. Pond at Gadder House ; Forth and Clyde Canal; Fossil marsh. P. 7 10. 



76. ORCHIDACE^E. 



1. MALAXIS. Bog-Orchis. 



M. PALUDOSA, Sw. A small weak plant, 3 in. high, rising 

 from a little tuber. Le. radical, oval, concave, extremely papillose. 

 Fl. in a small greenish spike, 2 sep. erect, the third recurved. 

 Lip superior, concave, acute, shorter than the sep., embracing the 

 column by its base. 



Very rare. In spongy bogs. (B) P. 7 9. Near the head of Loch Lomond, 

 and in the island of Arran. 



2. EPIPACTIS. Helleborine. 



1 E. LATIFOLIA, Sw. Broad-leaved Helleborine. Stem erect, 

 1 3 ft. high. Le. broadly ovate, strongly ribbed, lower ones 



