THE PLAN OF THE FLOWER. 85 



3. Redundancies, 



a, In the multiplication of organs, 

 6, In appendicular organs. 



4. Union of parts. 



a, By cohesions, 

 by By adhesions. 



5. Irregularities of development, 



• a, In homogeneous parts, 



b, In the receptacle. 



6. Combined deviations. 



We shall consider thes3 several topics in their order. 



418. The radical number of the flower is that which enumerates the parts 

 composing each whorl. It varies from one to twenty, and is expressed thus : 

 V, \/, V, V> etc., which mathematical expressions are to be read by the words, 

 dimerous (.5«r, two, ft:poc, part), or 2-parted ; trimerous, or 3-parted ; 4-merous, or 

 4-parted; pentamerous, or 5-parted ; G-merous, or 6-parted, etc. 



419. Exogens and endogens DISTINGUISHED. Pentamerous (V) flowers, like 

 the rose, flax, when each whorl is (naturally) 5-parted, are more generally charac- 

 teristic of the exogenous plants, V flowers of the endogens, as the lily, Trillium. 

 The flowers of Fuchsia aro V) of Circaea V, and of Hippuris 1 V. 



420. Deficiencies. Incomplete flowers often occur. They lack some one or 

 moro entire sets of organs. "When only one of the floral envelops, the calyx, ex- 

 ists, the flower is said to be apdalous or monochamydeous (x?.a[ivr, 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, tho flower is said to be 

 aclilamydeous or naked, as in lizard-taiL (264.) 



267 236 2(6 201 



264, Flower of Saururus (lizard-tail); achlymydoous. 265, Flower of Fraxinus (ash). 266, 

 Flower of Salix (willow), staminate. 267, pistillate. 



421. Imperfect flowers are also of frequent occurrence. They are deficient in 

 respect to tho essential organs. A sterile or staminato flower (denoted thus £ ) has 

 etamen3 without pistils. A fertile or pistillate flower ( $ ) has pistils without sta- 

 mens. Such flowers being counterparts of each other, and loth necessary to the 

 perfection of the seed, must exist either together upon the same plant or upon sep- 

 arate plants of the same species. In the former case the species is monoecious (8 ) 

 as in oak ; in the latter case dioecious ( £ $ ) as in willow. Tho term diclinous, de- 

 noting either Q or $ $ without distinction, is in common use. 



