XlV INTRODUCTION. 



64. The Corolla is usually of a thinner texture than the calyx, and variously 

 colored. Its leaves (Petals), when of the same number as the sepals, always 

 alternate with them. They are also often united by their contiguous margins, to 

 form a monopetalous corolla. 



65. When the calyx and corolla are so nearly alike as not to be readily dis- 

 tinguished, they are collectively termed the Perianth. 



66. A flower is complete when all its parts are present ; incomplete, when the 

 floral envelopes, or a part of them, are wanting ; perfect, when the stamens and 

 pistils are borne in the same flower ; imperfect, or diclinous, when they are borne 

 in separate flowers ; regular, when the sepals or petals are of uniform shape and 

 size ; and irregular, when they are unlike in shape or size. 



67. Imperfect flowers are further distinguished into moiwecious, when those fur- 

 nished with stamens (staminate or sterile flowers) and those furnished with pistils 

 (pistillate or fertile flowers] are borne on the same plant; dioecious, when they are 

 borne on separate plants ; and polygamous, when both perfect and imperfect flow- 

 ers are borne on the same or different individuals. 



68. The manner in which the parts of the floral envelopes are arranged with 

 respect to each other in the bud is termed their Estivation. They are valvate, 

 when their contiguous margins meet, without overlapping ; induplicate, when 

 these project inwardly ; reduplicate, when they project outwardly ; imbricated, 

 when the margins of one overlap the adjacent margins of the two next within ; 

 convolute, or twisted, when one edge of each piece covers the margin of the one 

 next before it, and the other edge is covered by the margin of the one next after 

 it ; and plaited, when the parts are folded lengthwise. 



7. The Stamens. 



69. A Stamen consists of a sac, called the Anther, and, usually, a stalk, called 

 the Filament, by which it is supported. 



70. They are hypogynous, when they are inserted on the receptacle ; perigynous, 

 when on the calyx ; epigynous, when on the ovary ; epipetalous, when on the co- 

 rolla ; and gynandrous, when they are united with the style. They are, also, 

 often combined with each other, either into one set (monadelphous), or into two, 

 three, or more sets (diadelphous, triadelphous, &c.). 



71. The Anther is composed, commonly, of two united cells, which open in 

 various ways, and discharge a yellow, fertilizing powder, called the Pollen. The 

 part which connects the cells is the Connective. 



72. It is erect, or innate, when fixed by its base to the apex of the filament ; 

 adnate, when fixed to the filament by its whole length ; versatile, when fixed by 

 the middle to the apex of the filaments on which it turns as on a pivot : introrse, 

 when it faces inwardly toward the pistils ; and extrorse, when it faces outward ly 

 toward the petals. Occasionally, they are united into a tube (syngenesious). 



73. Between the stamens and the pistils is often a fleshy expansion, called the 

 Disk. 



8. The Pistils. 



74. The Pistils occupy the centre of the flower. They are inserted, singly or 

 in a whorl, on the receptacle ; or, when this is elongated or enlarged, they cover 

 its surface. 



