Plant Anatomy Flashcards
Classification of meristematic tissues (origin)
- Promeristem- apices of embryonic roots and shoots
- Primary- apical meristems, fascicular cambium, intercalary meristems.
- Secondary- interfascicular and cork cambium.
Classify meristematic tissues (position)
- Apical - tips
- Lateral - fascicular and cork cambium
- Intercalary- leaf base and base of uppermost internodes in monocot stems.
Functions of parenchyma
Storage of reserve food
Slow condution of food and water.
Rigidity in succulent plants
Chlorenchyma perform photosynthesis
Buoyancy and aeration of tissues
Features of collenchyma
Thickened angles due to pectin and cellulose
Living cells
Absent in monocot stems and root
Found as a complete cylinder below epidermis of young dicot stems, petioles and corners of angular stems
Name the two types of sclerenchyma
Sclerenchymatous fibres
Stone or sclerotic cells
Give features of xylem tracheid
- Single enlongated. Tapering
- Thick cell walls. Lignin. Mechanical strength
- Thickenings absent - simple or bordered pits which allow water to pass
- Main vascular tissue in gymnosperms and ferns
Features of xylem vessels or tracheae
- Multicellular. Larger diameter. Prosenchymatous cells joined end to end.
- Cell wall thickened variously. Lignin
- Cells connected when septum dissolves
Define tyloses
Long protrusions of xylem parenchyma which enter tracheae and block them
Features of phloem sieve tubes
- Non lignified prosenchymatous cells joined end to end
- Transverse walls have small holes( sieve pits)
- Cytoplasm vacuolated without nucleus
Adjacent cells remain connected through sieve pits by cytoplasm threads. Direct food transfer
- Sieve pits grouped into - sieve plates
- Colorless and insoluble carb- callous. Callus formed over sieve plate.
Companion cells
- Parenchymatous cells adjacent to sieve tubes
Pteridophyta and gymnosperms- albumen cells - Dense cytoplasm. Conspicuous nucleus.
- Cytoplasmic connection. Nucleus controls activity of sieve tubes and helps in food conduction.
On what do the no. And position of stomata depend?
Form of leaf and conditions regard to transpiration
What are hairs or trichomes?
Elongation of outer walls of the epidermal cells. May be simple, branched or star shape.
Radial vascular bundle features
- Radial - separate and alternate radii
- Separated by undifferentiated parenchyma or conjunction tissue
- Exarch.
Concentric vascular bundle types and eg.
Amphicribal or hadrocentric. (Ferns)
Amphivasal or leptocentric( monocot stems)
Conjoint vascular bundle types and eg.
Collateral - open ( strip of fascicular cambium present between xylem and phloem) and closed. Monocot and dicot stems.
Bicollateral - phloem present on both sides.
Cucurbitacea or gourd family
What are the parts of cortex in ground tissue system
- Hypodermis - collenchyma in dicots and sclerenchymatous in monocots. Support and strength.
. - General cortex - parenchyma or sclerenchyma.
Cells of outer layer contain chloroplasts.
3. Epidermis - single layer barrel cells. Living cells which contain starch. Starch sheath( stems) Casparian strip and passage cells ( roots)
Functions of cortex
- Slow movement and storage of food
- Rigidity to young parts
- Leucoplasts may be present. Food storage
- Metabolic functions
Functions of pericycle
- Gives rise to lateral roots and adventitious roots that arise from the stem
- In dicot roots, gives rise to part of wavy cambium ring for intrastellar secondary growth
- Mechanical strength and food storage
What is the intrastellar ground tissue called
Conjunctive tissue
What are the types of cells in the cambium ring?
Fusiform initials
Ray initials
Which cells form the inter fascicular cambium
Cells of the pith ray lying between the vascular bundles at the level of the cambium become meristematic and form the strip
What forms the secondary vascular bundles
Periclinal divisions of the fusiform intials forms cells toward the periphery and the inner side of the cambium (pith)
What forms the secondary medullary rays
The ray initials give rise to parenchymatous cells in a thin narrow band which are arranged radially from the pith to the phloem. These are called the secondary medullary or vascular rays
What are the three parts of the periderm
The cork cambium or phellogen formed by the activity of the cells of the hypodermis which become meristematic
The daughter cells on the outer side of the cork cambium called phellem
The cells in the inner side which get cut off and form parenchymatous tissue called phellodern
