OUTLINE OF STRUCTURAL BOTANY 21 
When these teeth are also serrate the Bee is (Fig. 20) 
Doubly Serrate 
Ge the merein3 is formed of teeth ith concave outlines as at Fig. 
CIAIC ISM 3 |e eee een LL) CIULIDEG, 
When the margin is Deomelcne as ae Fig. 99, it. ISS ys! ello) LEEITe 
When the border is formed of rounded teeth with convex outline 
tesa (Mes 24) ee em Onenatie 
The diminutive terms peraeulite and cremate. are used in place 
of dentate and crenate when the teeth are very small. 
ARRANGEMENT OF LEAVES. 
The disposition of the leaves upon the stem constitutes that part 
of botanical science technically known as Phyllotaxy, but to the 
non-technical it is the Arrangement of Leaves. 
Every part of botanical science is of great interest to one who 
intelligently investigates it and this science of Phyllotaxy is one 
which richly repays the investigator. But in this place we can 
only refer to the conspicuous facts of three forms of arrangement. 
They are: 
Ist. Alternate, when the leaves are inserted singly at each node of 
the stem, In each case the insertion may appear to be first on one 
side of the stem and next on the exact opposite side. More frequently 
they appear to be inserted in a spiral line and this, as a matter of fact, 
is the real insertion, even when the leaves appear first on one then on 
the opposite side. 
2d. They are said to be opposite when they are inserted in pairs, one 
exactly opposite the other on the stem. 
3d. They are in whorls or verticils, whorled or verticillate, when 
three or more are inserted at the same node, forming a whorl about 
the stem. 
Upon some stems leaves which are in fact alternate are so 
closely disposed that it is difficult to see their alternate arrange- 
ment. In such case the leaves are said to be scattered. 
THE FLOWER 
To the ordinary observer a flower is that gracefully formed group 
of colored petals and stamens surrounded at its base by a rosette 
of green bracts, which by its vivid hues, attractive shape and 
pleasant perfume seems to constitute the crowning glory of a plant. 
A more exact and perhaps a more useful conception of a flower 
is that which defines it as an organ essential to the inception and 
the perfection of the seed and therefore to the perpetuation of the 
plant species. 
In this sense the flower may not consist of gracefully formed 
