210 



MANUAL OF BOTANY 



moncecious, placed on the margin or surface of tlie frond, or in 

 t£e axils of leaves. Perianth none. Male flower with 1 or a 

 few stamens, which are often monadelphous. Female flower 

 consisting of a 1-celled ovary, with 1 or more erect ovules. 

 Fruit 1- or more-seeded, membranous or baccate, indehiscent 

 or sometimes dehiscent. Embryo straight, cleft, in the axis of 

 fleshy albumen. 



Distribution, Numbers, and Properties. — They inhabit cool. 



Fig. 974. 



Fig. 975. 



Fiff. 974. A monoecious head of flowers of a species of Duckweed {Lemna 

 mireor;, consisting of two male flowers, each of which is composed of a 

 solitary stamen with a quadrilocular anther ; and one pistillate flower in 



the centre ; the whole surrounded by a spathe. Fig. 975, Vertical 



section of the pistil of the same. 



temperate, and tropical regions. Illustrative Genera: — Lemna, 

 Linn. ; Pistia, Linn. There are above 20 species. Their pro- 

 perties are imimportant. 



Series 6. — Apoearpce. 



Order 30. Tbiubidace^, the Triuris Order. — Diagnosis. — 

 This is a small order of plants allied to Naiadaoese, but usually 

 to be distinguished by its rudimentary embryo. The flowers 

 are also sometimes perfect. 



Distribution, Numbers, amd Properties. — Exclusively found 

 in warm and tropical regions. Illustrative Oenera : — Triuris, 

 Miers ; Sciaphila, Blumie. There are 8 species. Their pro- 

 perties and uses are unknown. 



Order 31. Alismace*), the Alisma Order. — Character. — 

 Swamp or floating plants. Leaves narrow or with an expanded 



