THE STEM 
45 
bearing only the flowers, as in dandelion. It may be herbaceous (not 
woody above ground), woody, succulent or fleshy ; solid , hollow (flstular 
if herbaceous) ; straight, flexuose (zigzag), &c. ; cylindrical, terete 
(cylindrical tapering), angular, ribbed, winged ; smooth, prickly, warty, 
hairy (for terms see Leaf, below). Polymorphism if any, form and texture 
of bud and bud-scales, growth in thickness, size and habit, bark ( smooth , 
scaly, warty , &c.), colour, and other points must also be described. 
Phyllotaxy, or the arrangement of the leaves upon the 
stem, is according to definite rules, especially in flowering- 
plants, though it varies within certain narrow limits. 
Leaves may be several at each node, when they are said 
to be in whorls , or two at each node (usually opposite ), or 
one ( alternate ). When the stem is so short that the leaves, 
as in the primrose or dandelion* are all crowded together 
and spring from the level of the ground, they are said to be 
‘radicals In the first two cases, as a rule, the leaves at 
one node stand above the gaps between those at the node 
below. In the case of alternate leaves there is found to be 
a fairly constant angle between each leaf and the next one 
above it, e.g. in Plantago (fig. 2) this angle is f of the whole 
circumference measured the nearest way. This fraction -§ 
represents the phyllotaxy of the plantain. A little considera- 
tion will show that (twisting of the stem excepted) the leaves 
will stand in 8 vertical 
rows, each divided 
from the next by of 
the circumference. For 
if we start from any 
leaf 1 and pass by the 
nearest way through all 
consecutive leaves till 
we come to leaf 9, this 
must be above 1 again. 
Leaf 2 will be §, 3 will 
be 4 , 4 will be 4 , 5 will 
be 6 will be 7 
will be -j-, 8 will be 
and 9 will be of the 
circumference from leaf 
1, i.e. immediately over 
it, and three turns of the spiral above it. Hence the rule for 
determining phyllotaxy : start from any leaf A and draw a 
Fig. 2. 
Phyllotaxy. 
