INTRODUCTION. 



Considering them, therefore, as leaves arranged in whorls on a base or 

 short thickened axis called the receptacle let us look into the 

 arrangement of a simple typical flower, one in which all the parts are 

 present and in the simplest form. We will commence our examination 

 below and work upwards. 



64. The Calyx is the lowest or outermost whorl of the leaves of the 

 flower. (Fig. 21a.) It is usually green in color, but not always, and its 

 principal function seems to be the protection of the parts within, espe- 

 cially while developing in the bud. Its parts may be united by their 

 edges, forming a tube, or separate, in which case they are called sepals. 



65. The Corolla is the whorl next above or interior to the calyx 

 (Fig. 27#), and is usually of more delicate structure, and of some other 

 color than green. Its parts may be separate, when they are called 

 petals, or they may be united by their edges, when the flower is spoken 

 of as monopetalous, in distinction from polypetalous. Again, they may 

 be very dissimilar in shape and size, when the corolla is said to be irregu- 

 lar. It is usually easily recognized by its delicate structure and high 

 coloring. Sometimes the corolla is wanting, when the flower is said to 

 be apetalous. 



66. The functions of the corolla are probably two- fold; protection 

 to a certain extent to the parts interior to it, and, it would seem prin- 

 cipally, attraction by means of its bright colors for insects and hum- 

 ming birds, which in the grand economy of nature are the pollen-bearers 



miniature match-makers in reality 

 for all of the brightly colored or 

 fragrant flowers. It would be interest- 

 ing in this connection to notice how 

 nicely flowers are formed with refer- 

 ence to that particular end i. e., for 

 insuring cross-fertilization through 

 the agency of these tiny messengers 

 wholly unconscious of the part they 

 are playing. But that the reader 

 must learn elsewhere or see for him- 

 self in the field. 



67. The calyx and corolla are spoken 



of as the perianth, or, from the fact of their enveloping the essential 

 organs, as the floral envelopes. They are considered as unessential organs, 

 because the elements of reproduction do not occur in them, and one or both 

 are often absent. In the latter case the flower is said to be naked. When 

 only one is absent that is considered as the corolla, and in such cases the 

 remaining calyx is very commonly highly colored and petal-like. Some- 

 times when both are present they are both highly colored and very nearly 

 alike. Rarely as in the marginal flowers of the Hydrangea, etc., they 

 constitute all there is to the flower, i. e., the essential organs are absent, 

 and such flowers are from that fact neutral. 



68. The Stamens sometimes spoken of collectively as the Androe- 

 cium, constitute the whorl next above or interior to the corolla, and so 



Fig. 27. Parts of a Flower detached from the receptacle, but relative positions maintained, 

 a, sepal one of the leaves of the calyx; b, petal one of the leaves of the corolla; c, 

 stamen; d, pistil. (From Gray.) 



FIG. 27. 



