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LEAVES (TISSUES image (COLLENCHYMA (Collenchyma cells also function in…
LEAVES
TISSUES 
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XYLEM
xylem transport water and minerals through the vessel elements and tracheids, which are dead at maturity and have a primary and secondary cell wall. In pits, the secondary wall is thin or missing, allowing water to flow laterally.
SCLERENCHYMA
Sclerenchyma mainly consist of dead cells that have primaryand secondary cell wall that provide support.Two types of sclerenchyma cells exist: fibers and sclereids.
PHLOEM
phloem transfers sugars and other items. in Angiosperm, seive tube element contain the sugar solution. sieve tube cells are surrounded by various support cells.
PARENCHYMA
Parenchyma cells are unspecialized cell that carry out most of the plant's metabolism. Parenchyma cells with chloroplasts are called chlorenchyma cells.Storage of starch, protein, fats, oils and water .
PARTS OF LEAVES
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STIPULES
two small flaps that grow at the base of the petiole of some plants. In some plants, the stipules grow quickly, enclosing and protecting the young blade as it develops. Some stipules, such as those of willows and certain cherry trees, produce substances that prevent insects from attacking the developing leaf.
THE BLADE
Board, flat part of leaf. photosynthesis occurs. many chlorophyll present.
THE PATTERN OF VEINS
NET VEINED
pinnate (featherlike)
Pinnately veined leaves have one large central vein, called the midrib, which extends from the base of the blade to its tip. Other large veins branch off on each side of the midrib. The leaves of beech, birch, and elm trees have such a vein pattern.
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NOT NET VEINED
Narrow leaves and needle leaves are not net-veined. Narrow leaves have a parallel-vein pattern. Several large veins run alongside one another from the base of the blade to the tip. Small crossveins connect the large veins. Needle leaves are so small that they have only one or two veins running through the center of the blade.
THE NUMBER OF BUNDLES PER LEAF
SIMPLE LEAF
A leaf with only one blade, Apple and oak trees, grasses, and many other plants have simple leaves.
COMPOUND LEAF
A leaf with more than one blade is known as a compound leaf. The blades of a compound leaf are called leaflets.
THE TYPES OF EDGES
TOOTH
Small jagged points along the blade edge, some have hydathodes that release excess water from leaf.
LOBED
The edge of such a leaf looks as if large bites have been taken out of it. this lobing helps heat escape from the leaf.
SMOOTH EDGE
almost all narrow, grass like leaves and needles leaves have a blade with smooth edges, particularly found in leaves native to warm climate.
STRUCTURE OF LEAVES
leaves consist of cuticle, epdermis, mesophyll cells, stoma, guard cells, airspace, vascular bundle and bundle sheath .
`Cuticle is the outermost layer where the light strikes. Epidermis is the inner layer which protects the internal structure of leaf and prevent the loss of water. Mesophyll cells are mede up of parenchyma which consist of chlorophyll containing chloroplast which help in photosynthesis process. Stomata helps in the gaseous exchange. guard cells help in the opening and closing of stomata. Vascular bundle consist of xylem and phloem. The bundle sheaths regulate the movement of substances between the vascular tissue and the parenchyma and, in leaves, protect the vascular tissue from exposure to air.
C3 LEAVES
Bundle-sheath cells surround the viens, bundle sheath are non photosynthetic, the first product of photosynthesis is a 3 carbon compound i.e. phosphoglyceric acid (PGA)
SUN LEAVES
Thicker, develop longer palisade cells or an additional layer of palisade cells.
C4 LEAVES
the bundle sheath cells contain chloroplasts, photosynthetic in nature, the first product of photosynthesis is a 4 carbon compound i.e oxaloacetic acid (OAA)
SHADE LEAVES
larger and thinner, often appear a darker green