SUPPRESSIONS, ALTERATIONS, APPENDAGES 2 1/ 



435. Petal-like sepals 

 of clematis. 



309. Undeveloped Organs. A flower may depart from 

 the normal type either by the non-development of parts, 

 or through the suppression or alteration of 



parts already developed. A want of develop- 

 ment generally characterizes simple and 

 primitive forms such as. the naked flowers 

 of the lizard's tail (Saurtmes), the black ash, 



and willow, in which the ftJ oTSJ 



floral envelopes are entirely rurus ( a f ter 

 ... ' GRAY). 



lacking, or reduced to a 



mere scale or bract. A step higher in 

 the order of development the floral envel- 

 opes appear, but are usually inconspic- 

 uous and without differentiation into 

 calyx and corolla, as in the elm, knot- 

 weeds, docks, etc. Where only one set of these organs is 

 present, it is considered a calyx, no matter how large and 

 conspicuous it may be, as in the four-o'clock, and clematis. 



310. Unisexual Flowers. Where one of the essential 

 organs is lacking, the flower is unisexual, which means that 

 either stamens only, or pistils only, occur in the same 

 flower. When the stamens alone are 



present the flower is said to be stam- 

 inate, or sterile because it is incapable 

 of producing seeds of its own, though 

 its pollen is a necessary factor in their 

 production. If, on the other hand, the 

 ovary is present and the stamens 

 absent, the flower is pistillate and fer- 

 tile ; that is, capable of producing fruit 

 when impregnated with pollen. Some- 

 times both stamens and pistils are 

 wanting, as in the showy corollas of 

 the garden " snowball " and hydrangea, and the rays 

 of the sunflower. Such blossoms are said to be neutral, 

 from the Latin word neuter, neither, because they have 

 neither pistils nor stamens. They can, of course, have no 



436 437 



436, 437. Flowers of 

 willow : 436, pistillate ; 

 437, staminate. 



