<5 
Aug. 1, 1902.] Sup2)lement to the " Tropical Agriculturist.'" 147 
Let us take the stem as the most convenient 
part to start with and note certain facts about it- 
THE STEM. 
A s'em may be erect, that is it may stand 
upright from the ground. Most large trees liave 
stems of this kind. 
An erect stem mny be unbranched as in the 
coconut or branched as in the mango. In the 
coconut observe that all the leaves are borne at 
the top of the unbranched stem; in tlie mango 
the stem divides and sub-divides into branche? of 
decreasing size, and the leaves are borne by the 
smallest twigs. Notice the unbranched and 
branched stems of trees near your school ; observe 
that some trees are more branched than others, 
that the method of branching regulates the shape 
of the tree (compare the ironwood with the 
banyan tree), and that some trees, like the wild 
breadfruit, form a denser shade than others like 
the suriya tree. 
A stem may be hard and woody. This is the 
case in trees which last a long time, as most 
forest trees. Many of these hard stems consist 
of wood yielding useful timber for building and 
other purpo.-es. The Uorest Department looks 
after such trees in our forests, and sees that the 
supply of useful wood does not become exhausted. 
Make a list of as many useful woods as you know, 
and say what they are used for,] 
A stem may be very tall as in the red-flowered 
cotton tree, or inclined to be short as in the casliew- 
nut tree; it may be tliin as in the arecanut or 
thick as in the coconut, or very thick as in some 
timber trees as Hora ; it may have a rough bark 
as in mango or smooth as in the gauva, 
But there are many stems which are more or 
less soft and pliable. la the young stage the 
stems of all trees are of this character, while 
plants which last only for a short time, and do 
not grow to any size, have also soft stems. 
Most of the vegetables you grow in your school 
garden are instances of the lattei', e.g., spinach. 
A stem may be contracted, that is undeveloped 
in length, so that the leaves are more or less 
brought together, as in lettuce, or the common 
"aloe." Observe the plants with contracted 
stems near the school, and notice that before they 
flower their stems become elongated and bear 
leaves separated from one another. This is well 
seen in the lettuce. 
Some stems are so slender that they cannot 
grow erect. Such stems may creep along the 
ground, as in the case of the sweet potato, or 
support themselves by twining round other trees 
as does the common long bean. 
The long bean, like most twining plants twines 
from left to right. [Do you know of a plant 
that twines from right to left ? If not, try and 
find one.] The grape vine has got some of its 
branches specially adapted for supporting itself. 
These branches sre in the form of coils which 
atach themselves to any support. In the 
common creeping Bignonia the branch is modified 
to form a claw-like structure consisting of honks 
for climbing, [Hence the specific name of the 
plant, viz., unguis-cati, signifying the claw of a 
cat.] All these structures should be carefully 
exmaiued. Leaves are also modified to enable stems 
to support themselves, but of these we shall speak 
later. Some trees (like the Allamanda) have no 
special arrangements for climbing but scramble 
up other trees for support. 
The stem of a tree sometimes bears sharp struc- 
tures which are modifications of parts of the stem. 
The thorn of the orange is a strong woody 
structure, which, much as you may try, you can- 
not break off with your hand. The prickle of the 
rose on the other hand is a superficial outgroivth 
that can be removed without very great difficulty. 
Stems do not vary much in colour, being generally 
green when young and brownish when old, but we 
have a red stemmed spinach. Do you know of 
other exceptional cases? 
Stems are usually cylindrical. Some are square 
(madurutala), or triangular as in many sedges 
(e.g., Tunhiriya), Exceptionally it is very irregular 
in form as may be seen in the different varieties 
of Prickly Pear (Katupathok) which takes very 
strange forms, being flat and leaf-like in the 
common variety. 
The stem is, as a rule solid, but some stems are 
hollow as in the bamboo (una-gas). 
Besides the stems that we find above ground, we 
have also underground stems, some thin and long 
as in the common conch grass (etora); others thick 
and short as in ginger (inguru); others again much 
swollen and sometimes forming large masses as in 
the yams. Such swollen underground stems can 
be distinguished from swollen underground roots 
like the radish (rabn) or manioc (raanyoka) by 
the former having scaly leaves as in arrowroot 
(hulunkiriya) or minute buds as in the potato 
(arthapal). In the onion the stem is reduced to a 
Tery small structure round which the succulent 
leaves which envelope it are closely packed. 
THE ROOT. 
The parts of a plant which grow underground 
are generally spoken of as the roots. 1 hive told 
you, however, that there are cases of underground 
stems such as the common conch grass (etora) which 
is such a troublesome weed because every piece of 
the underground stem left in the soil gives rise to a 
new plant. True roots have not this power of 
growing. 
But there are also cases of roots which are pro- 
duced above ground. Such are the hanging roots 
of the banyan (maha-nugaj and the thick roots 
given out by the screw pine (wetakeyia), which 
tend to reach the ground and become fixed in it. 
Notice that the hanging roots of the banyan 
eventually become woody and stem-like, so that 
the tree appears to be supported by a number of 
columnar stems. The old underground roots of 
large trees also become hard and woody like the 
stem, and give rise to new plants, like the breadfruit 
tree and other trees that you may know of. Hard 
woody roots sometimes grow out of the giouud 
almond plank-like structures as in the Java 
forming (kekuna). 
When speaking of plants with climbing stems I 
told you that there were other arrangements for 
climbing besides those I mentioned in the lesson 
on the stem. Well, plants sometimes climb with 
the aid of roots. Pothos (potawel) commonly 
found on jungle trees, climbs by means of its roots 
which attach themselves to the back of trees. The 
