58 SOUTH AFRICAN BOTANY 
same straight line. This falseaxis is called aSyMPoDIUM. 
It can be distinguished from a true racemose form by 
noting the position of the leaves in the axils of which 
the lateral branches originated. In the helicoid cyme 
the lateral branches are all produced on the same side. 
In the false dichotomy form two lateral branches are 
produced at the same level and the main axis terminates 
immediately after the branching. 
Most trees Have cymose forms of branching. 
PRACTICAL EXERCISES. 
1. Examine the tuber of the Jerusalem artichoke. Note 
the buds which serve to identify it asa stem structure. Sketch 
the tuber, showing the buds and scale leaves. 
2. Examine a potato in the same way. Cut a section of 
one of the buds, and drawit. Test the surface of a cut potato 
for starch with iodine solution. 
3. Cut an onion bulb in half longitudinally. Sketch same, 
showing the scale leaves, the swollen leaf bases, the short stem 
and swollen disc, the adventitious roots, and the developing 
foliage leaf. 
4. Cut transverse sections of the stem of the sunflower 
(Helianthus annuus) and of the broad bean (Vicia faba) preserved 
inalcohol. Soak the sections in water for a minute or two, and 
then place the thinnest section on a slide, add one drop of 
Schultze’s solution and examine under the low power, Sketch 
the section showing— 
(a) Epidermis ; 
(b) Cortex and endodermis ; 
(c) The central cylinder, with its ring of vascular bundles, 
the medullary rays, and the pith. 
Also examine a single bundle under the high power, and 
make out and sketch the phloem (empty sieve tubes and com- 
panion cells filled with protoplasm) phloem parenchyma, cam- 
bium, and xylem. 
5, Cut asmall piece of stem in half longitudinally and eut 
