MONOCOTYLEDONS: ORCHIDALES. 



66 S 



Cut off a portion of the corm. Do not eat any portion, but touch the 

 tongue to the cut surface. The flesh of the corm is very acrid. 



Material. Freshly collected plants should be used, the entire plant; 

 small ones as well as large ones. 



1156. Related to the arum family are the "duckweeds." 

 Among the members of this family are the most diminutive of 

 the flowering plants, as well as the most reduced floral structures. 

 (For description and illustration of three of these duckweeds, 

 see Chapter III.) 



Other related families are the cat-tails and palms. In the 

 latter the spathe and spadix are of enormous size. The cocoa- 

 nut is the fruit of the cocoanut palm. 



Topic IV: Monocotyledons with large petals and 

 irregular flowers. 



ORDER ORCHIDALES. 



1157. Lesson V. The orchid family (Orchidaceae). In the orchids 

 are found the most striking departures from the arrangement of the flower 

 which we found in the 



simpler monocotyledons. 

 An example of this is seen 

 in the lady-slipper (Cypri- 

 pedium, shown in fig. 467). 

 The ovary appears to be 

 below the calyx and co- 

 rolla. This is brought 

 about by the adhesion of 

 the lower part of the 

 calyx to the wall of the 

 ovary. The ovary then 

 is inferior, while the 

 calyx and corolla are 

 epigynous. The stamens 

 are united with the style 

 by adhesion, two lateral 



perfect ones and one upper imperfect one. The stamens are thus gynan- 

 drous. The sepals and petals are each three in number. One of the petals, 

 the "slipper," is large, nearly horizontal, and forms the "lip" or "label- 

 lum" of the orchid flower. The labellum is the platform or landing-place 

 for the insect in cross-pollination (see Chapter XLIII, Pollination). Above 



Fig. 552. 



Flower of an orchid (Epipactis), the inferior ovary 

 twisted as in all orchids so as to bring the upper part 

 of the flower below. 



