INTRODUCTION 
Primrose, or adherent to the carpels in a central column , as in Orchids. 
The stamens are commonly equal in length ; but if in two circles, as in 
the Purple Loosestrife, these circles are often of different length ; and in 
the Family Labiatce , the Mint and Thyme group, there are four stamens 
developed, two longer than the other two, or didynamous (Greek St-, di-, 
two; Sumyut?, dunamis , strength), whilst in the Crucferce, or Wallflower 
Family, there are six, four — or more truly two deeply bifurcate ones — long 
and two short ( tetradynamous ). The various forms of the filaments and of 
the anthers, the attachment of one to the other, and the ways and direction 
in which the anthers split when ripe, are also characters of importance in 
discriminating groups. 
The pollen is usually abundant and in very minute, smooth, round, 
dry granules in those less conspicuous flowers, such as those of grasses and 
catkin-bearing trees, in which it is carried by wind ; and scantier and in 
somewhat larger granules of various forms, with projecting points or ridges, 
waxy and coherent, in those flowers which are visited by insects. 
The carpels occupy the centre of the flower. There may he only 
one, as in Peas, Beans, Cherries, etc. {monocarpel l ary) , or any other number 
{polycarpel/ary), often two, three, or, if arranged spirally, as 
in a Buttercup, a much larger number. When more than 
one, the carpels may be free from one another {apocarpous), as in the flower 
just mentioned, or united {syncarpous), as in a Lily, an Orchid, or a Violet. 
In either case, the carpel, which is essentially a leaf, consists typically of 
three regions — the broad basal portion, which forms, or contributes to form, 
the ovary ; a narrower, tubular portion, or style; and the sticky extremity, or 
stigma, which receives the pollen carried by wind, insects, or other means. 
When the carpels are apocarpous, as in the Columbine or Strawberry, each 
forms a distinct ovary, style, and stigma ; whilst when there is only one 
carpel, as in the Pea, it is easy to trace the midrib and lateral veins of the 
carpellary leaf, and to realise that the young peas, the ovules, afterwards to 
become the seeds, spring from its united inrolled margins. These form a 
spongy ridge projecting into the cavity of the ovary, which is termed the 
placenta. When the carpels are syncarpous, their union may occur in any 
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