Dr. Babasaheb Ambedkar Marathwada university, Aurangabad, maharashtra, syllabus of B. Sc. Botany First year (Semester-I, paper-II

1. Morphology of Angiosperms - 2
Stem
Dr. A.S. Naik
Head, Dept . of Botany
S.B.E.S. COLLEGE OF SCIENCE

2. What are stems?

3. Types of stems

5. Forms of stems

6. Culms and Caudex
Euphorbia caudex
Bamboo culms

8. Modifica;ons of stem

10. Bulbs and Tubers
Bulb of Onion Tubers of Potato

11. Corms
Yam-Elephant foot corm
Amorphophallus Colocasia corm-arbi

12. Rhizome
e.g. Ginger, Turmeric

13. Aerial modificaIons
Thorns: e.g. Indian Plum
• Axillary buds modified.
• Long/short, sharply
pointed structures
• Give protec;on
Tendrils: e.g. Passiflora
• Axillary buds modified into
• coiled wiry tendils.
• Found in weak stemmed
plants.
• Help in climbing on hosts.

14. Aerial modifica<ons-contd.
• Phylloclads of Opun*a • Phylloclades:
1. Greek: Phyllos-leaf, klados-
branch.
2. A flaQened stem resembling a
leaf
3. Performs photosynthesis.
4. Leaves modified into spines.
5. FlaQened green stems also
holds water.

15. Cladodes
• Cladodes:
1. La;n-Kladodes=having many
shoots.
2. A phylloclade of one or two
internode
3. a flaQened leaf like stem arising
in the axils of a minute, bract-like,
true leaf.
Cladodes: e.g. Asperagus

16. Cladophylls
• Cladophyll of Ruscus.
“Cladophylls,” or highly
modified stems that have
been flaQened to
essen;ally serve the
purpose of a leaf.

17. Bulbils
• Bulbils: e.g. Dioscoria
1. A speical mul;cellular body
developed from floral/axillary
bud,meant for reproduc;on.
2. The axillary bud develops into a
bulbil.
3. This bulbil detaches from the
mother plant and grows up into a
new independent plant.

18. Sub-aerial modifica;ons

19. Stolons
•
• Lateral branches called stolon
originate from the
underground stem.
• Grow horizontally outwards
for a varying distance in the
soil.
• Ul;mately emerges out of the
ground and develops into a
new plant.

20. Runner
• The runner arises from the
base of the stem as a lateral
branch
• Runs along the surface of the
soil. Dis;nct nodes and
internodes. At each node
produces roots below and
leaves above.
• Many runners are produced
by the mother plant and they
spread out on the ground on
all sides.
• Upon separa;on of a runner,
they are capable of growing
independently.
E.g., Oxalis, Fragaria,
Centella asta<ca, Mentha

21. Offset
• An offset is a short
thick runner like
branch which produces
a new plant at its ;p.
• The offsets grow in all
direc;ons from the
main stem of the
parent plant.
• If any injury results, it
is capable of leading an
independent
existence. E.g., Pis;a,
Eichhornia.

22. Sucker
• A lateral branch arising
close to the ground level.
• Traveling underground
for some distance.
• Turning up at its end and
producing a new plant is a
sucker.
• Eg. Chrysanthemum