stem stems are adapted to different environments. underground stems modified for food storage ex:...
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STEMStems are adapted to different environments.
Underground stems
Modified for food storage
ex: white potato (tuber)
Climbing stems (tendrils)
ex: strangler fig tree
Runner stems
Runs along the surface of the ground and reproduce quickly by asexual reproduction
ex: strawberry
Cladophyll
Modified for water storage and photosynthesis
ex: cactus
STEMUnderground
stems
Climbing stems (tendrils)
Runner stems
Cladophyll
Types of Stems
Herbaceous stems
are soft, green and juicy
usually live for 1-2 years
is seen in two groups of
plants
Woody stems
are made up of thick and though tissue called wood
normally live more than 2 years
almost all of them are dicots
ex: oak tree, maple treemonocots
no vascular cambium
vascular tissue is scattered irregularly
ex: corn
dicots
has vascular cambium
vascular tissue is arranged in a circle
ex: bean, sunflower
Types of Stems
Herbaceous stems Woody stems
monocots dicots
Monocot and Dicot Stems Flowering plants seeds have at least one seed leaf called
cotyledon, that stores food.
Some seeds have one cotyledon and the plants that grow from these seeds are called dicots.
Some seeds have one cotyledon and the plants that grow from these seeds are called dicots.
ex: corn monocot bean dicot
Monocot and Dicot Stems
Monocot stems Dicot stems
fundemental tissue vascular cambium
Monocot and Dicot Stems Monocot stems Dicot stems
Monocot and Dicot Stems
Epidermis: protects the stem of herbaceous monocot and dicot plants. Cork protects the stem of woody (dicot) plants.
Cortex: made up of parenchyma cells to support the stem and store food in dicot plants.
Fundamental tissue: composed of parenchyma cells. In monocots, the fundamental tissue is not separated into pith and cortex.
Vascular cambium: produces new xylem at the inner side and new phloem at the outer side in dicot plants.
Monocot and Dicot Stems
*** In a woody dicot stem, xylem produced by vascular cambium builds up as the new xylem is added and these compose annual rings of a tree. In this way plant grow wider. But phloem doesn’t build up as new phloem is formed. Because older phloem break off as layers when new ones are added.
*** Because monocots don’t have vascular cambium, they don’t show secondary growth.
*** In woody stems lenticels which are unsuberized permits gas exchange. In herbaceous stems, stomata permit gas exchange.
Monocot and Dicot Stems
LEAF
Internal Structure of the Leaf
Mesophyll (Photosynthethic Tissue)
Upper portion of mesophyll
It’s one or two cell layers thick
Composed of tall, tightly packed cells filled with chloroplast
It’s the main site of photosynthesis
It’s below palisade layer
It’s made up of irregularly shaped cells
Between it’s cells there are large air spaces.
It’s cells have fever chloroplasts.
It’s main function is to allow diffusion of gases into the leaf.
PALISADE SPONGY
Internal Structure of the Leaf
TYPES OF LEAF
TYPES OF LEAF
Differences between Monocot and Dicot Plants
Seed leaves:
Monocots Dicots
Differences between Monocot and Dicot Plants
Flowers:
Monocots Dicots
Differences between Monocot and Dicot Plants
Leaves:
Monocots Dicots
Differences between Monocot and Dicot Plants
Stems:
Monocots Dicots
Differences between Monocot and Dicot Plants
Stems:
Monocots Dicots
Differences between Monocot and Dicot Plants
Roots:
Monocots Dicots
Differences between Monocot and Dicot Plants