AROIDE^E. 



217 



In Marsh Calla (Calla palustris], a common plant in 

 the north of Europe, the flowers are perfect, each con- 

 sisting of a pistil surrounded by about 6 stamens. In 



FIG. 162. Flower of Marsh 

 Calla. 



FIG. 163. Flower of Oron- 

 tium. 



Orontium the pistil and stamens are enclosed by a six- 

 leaved perianth. 



OBSERVE the extremely short and thick rhizome of 

 Arum, distinguished as a corm, containing much starch, 

 formerly collected in the Isle of Portland as " British 

 arrowroot," and sold at Weymouth at eightpence per 

 pound : the leaves, net-veined as in Dicotyledons. 



The large tubers of Colocasia antiquorum are cultivated 

 in tropical countries, and eaten like Yams ; they all 

 contain, as docs Antm, an acrid juice, which is removed 

 in cooking. 



Calla (Richardia} ^thiopica, a South African plant, 

 resembling the European Marsh Calla on a large scale, 

 with a beautiful white, funnel-like spathe, is very commonly 

 grown in parlour-windows. 



62. Natural Order Lemnacese. The Duckweed 

 Family. 



DISTRIBUTION. Waters of the northern hemisphere, 

 rare between the Tropics. One British genus, species 5. 



