396 THE ARALES 



curiously perforated leaves of the Monstera. Many species of 

 Anthurium are climbers and reach to the top of the highest 

 trees, sending out with great regularity from the successive 

 nodes, naked branches that may reach the ground and form roots. 

 The order is represented in temperate regions by a few very 

 familiar genera as jack-in-the-pulpit (Arisaema), skunk cabbage 

 (Spathyema), golden club (Orontium), sweet flag (Acorus), 

 water arum (Calla). The duckweeds that float upon every 

 pond are extremely reduced allies of the order, representing the 

 smallest seed plants known, Wolffia being an oval, rootless plant 

 scarcely one millimeter in diameter. 



The inflorescence is usually covered, as in Typha, with a bract 

 known as the spathe. This organ is variously colored and often 

 the most attractive feature of the plant. The coloration and 

 the odors and glands that are developed in some of the forms 

 indicate that these plants are entomophilous. The flowers are 

 arranged upon a fleshy axis, the spadix, and in the simplest forms 

 are quite comparable to those of the Typha, consisting of one or 

 a few stamens or a single pistil (Fig. 286, B-D). These im- 

 perfect flowers may be developed on different parts of the same 

 spadix or on different spadices. In more advanced types, the 

 flowers are perfect, containing one or several pistils that may 

 cohere and stamens which are surrounded by a very rudimentary 

 perianth. The relation of these plants to insects is a very inter- 

 esting one. The brightly colored spathe serves as an allurement 

 and it also protects the microspores against wetting. The spores 

 of comparatively few plants can endure water and it will be 

 interesting to observe in the following lessons the devices that 

 appear to guard against this danger. The spathe also affords 

 shelter to the insect and the temperature is higher within the 

 spathe since the food is being rapidly oxidized while the spores 

 are forming. The temperature of the larger spadices may ap- 

 proach blood heat, being 10 to 25° C. higher than the outside 

 air. Insects are not slow to avail themselves of these advantages 

 and they also find an abundance of food in the microspores and 

 glands that are often developed upon the spathe. Many aroids 

 are characterized by the foul odors of decaying flesh and it is 



