STEM Flashcards
The ______ develops to form the stem. Thus stem is an aerial part of the plant.
Plumule
Stem has got the following characteristics:
- It is ascending axis of the plant and
phototropic in nature. - It consists of nodes, internodes and buds.
- It gives rise to branches, leaves and flowers.
- Stems may be aerial, sub-aerial and
underground.
When the stems are thin and long, they are
unable to stand erect
Weak stems
Types of Weak stems
Creepers or Prostate stem
Climbers
Twinners
When they grow flat on the ground with or without roots, e.g. grasses, gokharu, etc.
Creepers or Prostate stem
These are too weak to stand alone. They climb on the support with the help of ten-drils, hooks, prickles or roots, e.g. Piper betel, Piper longum
Climbers
These coil the support and grow further. They are thin and wiry, i.e. ipomoea
Twinners
These are the normal stems and may be soft or hard a
Herbaceous and woody stems
Underground modifications of stems
Rhizomes
Tubers
Bulb
Corm
Grow horizontal under the soil
Rhizomes
characterized by the presence of ‘eyes’ from the vegetative buds
Tubers
the food material is stored in fleshy scales that overlap the stem
Bulb
generally stout, and grow in vertical direction
Corm
Sub-aerial modifications of stems
Runner
Stolon
Offsets
Sucker
These creep on the ground and root at the
nodes
Runner
These are lateral branches arising from the
base of the stems which grow horizontally
Stolon
These originate from the axil of the leaf as short, thick horizontal branches and also characterized by the presence of rosette type leaves and a cluster of roots at their bottom, e.g. aloe, valerian.
Offsets
These are lateral branches developed from underground stems
Sucker
Aerial modification of stems
Phylloclade
Thorns and prickles
Stem tendrils
Bulbils
At times, the stem becomes green and performs the function of leaves
Phylloclades
This is another type of aerial modification meant for protection.
Thorns and prickles
In certain plants, the buds develop into tendrils for the purpose of support.
Stem tendrils
These are modifications of floral buds meant for vegetative propagation, such as Dioscorea and Agave
Bulbils
Uses of stems
- either used as food spices or for culinary purposes.
- used as fodder.
- sources of industrial fibres used for various purposes.
- used as rubber.
- used as drugs.
- are injured to produce gums for their multiple industrial uses.
