LECTURES. 43 
all these questions, and I propose to-day to try and give some idea of 
the relation of plants to each other, and to shew you how to identify 
them. 
The first thing that is absolutely necessary is to know the parts of 
a flower. 
A {perfect flower, besides the essential organs, stamens and 
pistils, has sepals and petals. The green sepals protect the 
flower in bud, and often drop off when the flower opens. Poppy is 
a good example of that. When in bud the red petals are all tightly 
folded and concealed, but as the bud opens, and the petals spread 
out, the sepals drop off, they are no longer wanted. The petals are 
nearly always bright in colour, as their use is to attract insects. Some 
botanists think that certain insects are attracted by certain colours, 
and ingenious theories have been put forward to shew how different 
colours must have originated ; according to Grant Allen yellow was 
the first colour and blue is the last to be produced ; bees are supposed 
to have a special fancy to blue. Flowers which are visited by night- 
flying insects are totally white, so that they may be seen; very often 
they are also sweet smelling. Insects visit flowers in order to get their 
honey and in doing so they also get pollen, which they carry to 
another flower of the same kind, and thus cross-fertilisation i 
brought about. 
At first sight it seems as if the stamens and pistils are entirely 
different from sepals and petals; the poet-philosopher, Goethe, was 
one of the first to point out their real relationship. He shewed that 
sepals, stamens, and carpels all come off laterally from the stem. The 
idea first occurred to him while looking at a fern-palm at Padua. He 
was struck by the immense variety of changes of form which thé 
successively developed stem leaves exhibit, by the way in which the 
first simple root leaflets are replaced by a series of more and mor 
divided leaves, till we come to the most complicated. He afterwards 
succeeded in discovering the transformation of stem leaves into sepals) 
and petals, and, of course, sepals and petals into stamens, nectariesy | 
and ovaries.—Goethe’s Metamorphosis of Plants, 1790. 
More modern botanists argue that stamens are converted int 
petals, e.g., garden flowers ; c.f., a garden rose with a wild rose. 
- In botany anything that comes off laterally from a stem is calle 
a leaf; so that sepals, petals, stamens, and carpels are really leaves 
quite as much as the green leaves we all know so well; a botani 
speaks of these green leaves as foliage leaves, while sepals, etc,, f 
calls floral leaves, It is very important to be clear about this, as 
