224 
NATURE NOTES 
cohesion of frequent occurrence is between the carpels of the 
pistil. When these are free, as in a buttercup, the pistil is 
called “ apocarpous when they are coherent, it becomes 
“ syncarpous,” as in a poppy head. It is rarer to find the 
stamens coherent, but they are so in the mallow. Similarly are 
the sepals of the calyx sometimes united, as in the mallows and 
the pinks. 
In thesecond Sub-division, or Calyciflorae, the floral receptacle 
puts on a character which causes the petals and stamens to 
appear as if they arose from the calyx; hence the name. This 
“ receptacular tube ” has been already described in the case of 
members of the rose family. It was at first called the calyx- 
tube, and is so named in Hooker’s “ Flora ” ; but it is better to 
regard it as an outgrowth of the thalamus. Its use is to secrete 
honey, and it has probably arisen in response to the irritation of 
insects themselves. 
In the second Division the corolla always has its petals 
coherent, and represents a more advanced stage in the history of 
plants than that of the Polypetalae. The corolla may be, and 
more usually is, “ inserted ” upon, i.e., rises out of the recep- 
tacle ; but in some orders of Calyciflorae, such as the Umbelliferce, 
the ovary may be imbedded in a receptacular tube, and then the 
corolla appears to arise from the summit of the ovary, as in the 
Composites and in Campanulas. 
It should be also observed that it is a general rule that, 
when the corolla is “ gamopetalous,” the stamens are adherent* to 
the corolla-tube. The heath family Ericacecc and the Campa- 
nulacees furnish the only exceptions. 
Division III. is called Incompletae, because the flowers 
never have a corolla, and sometimes the calyx is wanting, while 
the stamens and pistil may be in different flowers. They are 
believed to be degraded forms, either of orders contained in the 
preceding divisions, or of which the ancestry is lost. 
SuB-CLASs II. is only represented here by one family, which 
contains the three shrubs or trees, the Scotch fir, the common 
juniper, and the yew-tree. 
They all agree in having no pistil wherewith to protect the 
ovules. These being therefore quite exposed, have suggested 
the word gymnospermotis, or “ naked-seeded.” 
This group is believed to be a very primitive type, and 
supplies the link between ferns and other “ cryptogams ” on the 
one hand, and the flowering or phaenogamous plants on the other. 
Class II., Monocotyledons or Endogens, can be best studied 
in conjuction with Class I., Dicotyledons or Exogens. The 
characteristics by which they are known are as follows : — 
Dicotyledons — Embryo with two cotyledons ; Axial root 
present ; Stem with distinct pith, wood and bark ; Leaves with 
netted-veined blades ; Floral whorls in twos, fours or fives. 
* If parts of any one whorl are united, they are said to be coherent ; if those of 
two distinct whorls arc joined together, they are adherent. 
