23, 24.] STUDY OF ANOMALOUS FLOWEKS. 29 



Those of Xyris (14) are ^/, having all the parts in 3s. 

 Xyris is one of the Endogens. Trimerous flowers are 

 characteristic of this great group of Plants, while pen- 

 tamerous flowers commonly distinguish the Exogens. 



66. Deficiencies often occur, rendering the flower 

 incomplete. Such flowers lack some one or more en- 

 tire sets of organs. When only one of the floral 

 envelopes, the calyx, exists, the flower is said to be 

 apetalous or monochlamydeous (#Aa^c, a cloak), as in 

 Elm, Phytolacca. These terms are also loosely applied 

 to such plants as Rhubarb, Anemone, Liverwort, where 

 the pieces of the perianth are all similar, although in 

 two or three whorls. When the perianth is wholly 

 wanting, the flower is said to be achlamydeous, or 

 naked, as in Lizard-tail (15). 



17 



15, Flower of Saururus (Lizard-tail) achlamydeous. 16, Flower of Fraxinus (Ash). 17, Flower 

 of Salix (Willow), staminate 18, pistillate. 



67. Imperfect flowers are also of frequent occur- 

 rence. They are deficient in respect to the essential 

 organs. A sterile or staminate flower (denoted thus $ ) 

 has stamens withous pistils. A fertile or pistillate 

 flower ( ? ) has pistils without stamens. Such flowers 

 being counterparts of each other, and both necessary 

 to the perfection of the seed, mast exist either to- 

 gether upon the same plant or upon separate plants 

 of the same species. In the former case, the species 



