rw} 
PART I.—STRUCTURAL. 3) 
and are therefore said to be sessile,* while their leaflets and 
segments become narrower and less toothed, and in some cases 
are reduced to a single leaflet. 
If we now examine the blade somewhat more closely we 
see that it is composed of a number of spreading veins from 
which numerous finer veinlets branch off, the whole forming a 
framework or skeleton of fine fibres on which the green tissue 
‘of the blade is spread out and supported. This is best seen on“: « 
~coresponding to the lobes, from which branches go off to each 
of the smaller segments. The arrangement of veins in a leaf- 
blade is termed its venation,{ and the particular kind occur- 
ring in the buttercup is netted or reticulated. | 
At the extremity of the more erect stems we find the 
flowers placed, one or more being produced from the axils of 
the upper leaves. Hach flower is on a furrowed stalk or 
peduncle, which is often several inches in length. Now 
take a flower and remove the individual parts, laying them 
out in rows in front of you. You will find there are four sets 
of organs, arranged nearly in a circular manner, constituting 
the flower, each of which—-as you will probably find out by 
other examples later on—is a modified leaf of some kind or 
other. ‘The outer set of leaves, which are also lowest down, 
are yellowish-green in colour. These are the sepals, and we 
speak of the whole set or whorl of five as the calyx. The 
next whorl, attached a little higher up, is composed of five 
shining-yellow leaves—the petals—together spoken of as 
forming the corolla. It is these that in popular significance 
constitute the flower. The third set of organs consists of a 
large number of slender stalks bearing yellow heads; these 
are the stamens. (If we wish to be very technical, we call 
the whole assemblage of these the androecium.) Having 
removed and arranged before us all these three sets of floral 
leaves, we find that there still remain numerous small green 
organs, like miniature short pea-pods, crowded on the very 
top of the flower-stem; these are the carpels, the whole 
group of them constituting the pistil. 
We may further notice at this stage that the top of the 
peduncle on which all these four sets of floral leaves are 
arranged is somewhat different from the portions below. 
This slightly-elongated portion is called the floral receptacle 
or thalamus. Before proceeding to examine in detail the 
different parts we have named, take another flower and cut 1b 
longitudinally into two halves. This is best done by splitting 
it with a sharp knife from the flower-stalk upwards through 
* Tat. sedeo, sesswi, to sit. 
+ Lat. vena, a vein. 
t Lat. reticulum, a little net. 
