The Structure of flowering plants

There are about 30,000 species of flowering plant Generally there is an underground root system and overground shoot system

3 Types of roots Tap roots – one main long root that comes from the radicle of the seed, lateral/secondary roots emerge from this and these usually have root hairs Common in Dicots

2 Fibrous Roots – formed when the radicle dies and leaves equal sized roots coming out of the stem Common in Monocots

3 Adventitious roots – these don’t grow from the radicle and are found in strange places! Fibrous roots and the gripping roots of ivy are in this category

Functions of the root Anchor plant in soil Absorb water and minerals Transport absorbed substances to the shoots Some roots store food eg. Carrots, turnip and radishes

4 zones in a root Zone of protection Zone of cell production (Meristematic zone Zone of elongation Zone of differentiation

XYLEM PHLOEM DIFFERENTIATION ROOT HAIRS EPIDERMIS ELONGATION MERISTEM CELL PRODUCTION ROOT CAP PROTECTION

Zone of protection Root cap protects cells

Zone of cell production has meristem cells that can divide and allow plants to grow Apical meristems are at tips of roots and shoots Lateral meristems are along the side of the plant

Zone of elongation When the meristem makes cells they are very small and go to this zone to grow longer Plant growth hormones stimulate this

Zone of diffferentiation The cells made by the meristem develop into different tissues These are Dermal tissue for protection Ground tissue found between dermal and vascular tissue (The flesh of the plant) Vascular tissue – Xylem and Phloem which transport minerals and water around the plant

Stems The stem is the main part of the shoot The stem carries leaves which emerge through points called nodes The part of the stem between 2 points is called an internode

The tip of the stem has a terminal or apical bud – causes the stem to keep growing at the tip Auxillary buds or lateral buds are located along the stem Lenticels are found on stems and are openings for gas exchange

Functions of Stems Support aerial parts of plants Transport water and minerals from the roots to the leaves and flowers Transport food made in the leaves to the roots They carry out photosynthesis when they are green They may store food

Leaves Some leaves do not have a petiole (they are joined directly to the stem) and are called sessile Veins emerge from the midrib and these veins contain transport tissue like xylem and phloem

Sessile Leaves (No Petiole)

Venation The pattern of veins is called venation and 2 types of venation are common

Parallel venation means that the veins run alongside each other Parallel venation means that the veins run alongside each other. This pattern is found most monocots e.g. grasses, daffodils and tulips

Net or reticulate venation means that veins form a branching network throughout the lamina. This pattern is common in dicots e.g. horse chestnut, rose and buttercup

Functions of leaves Photosynthesis Gas exchange Transpiration (water loss) Food storage e.g. grasses, lettuce and cabbage

Tissues in flowering plants When meristematic cells are going to divide they will specialise or differentiate into 3 categories of plant tissue Dermal Ground Vascular

Dermal tissue Location – Dermal tissue is like the skin on a plant e.g. epidermis Appearance – Epidermis cells are living, rectangular cells Function – To the protect the plant

Ground tissue This occupies the area between the dermal and vascular tissues in a plant This makes up most of the bulk of the young plant It carries out a range of functions such as photosynthesis, storage of food and wastes and gives strength and support to the plant

Vascular Tissue Vascular tissue transports materials around the plant It is a complex tissue because it consists of 2 types of cells xylem – water and mineral transport Phloem – transports food (products of photosynthesis

Xylem Xylem is made up of 2 main types of cells, vessels and tracheids

Xylem tracheids Are long tapering cells whose insides are hollow at maturity They overlap and allow water to pass from tracheid to tracheid through thin parts of the wall called pits

Phloem Sieve tubes transport food made by photosynthesis from the leaves to the rest of the plant Companion cells control the activities of the sieve tube elements Phloem is found in the vascular bundles of roots, stems, leaves and flowers

Where are the different tissues in the root??

Where are the different tissues in stems??