1. Plant Structure

2. There are many types of plants….
We are going to focus on land plants: - they provide protection for their embryos which has increased over time - they have multicellular haploid and diploid phases - they can be compared by the presence o absence of conductive systems

4. Types of Land Plants Plant Group Major Features Non-vascular
no conducting tissue
often grouped together as bryophytes
usually small and grow close to the ground
include mosses, liverworts, and hornworts
Seedless
Vascular
Plants
well-developed vascular tissue
do not produce seeds
include horsetails, ferns, club mosses, and whisk ferns (were once large specimens, but most of today’s representatives are relatively small)
Seeded
Vascular Plants
most living plant specimens are in this group
seeds contain an embryo, a supply of nutrients, and a
protective outer coat
have extensive vascular tissue and include some of the
world’s largest organisms

5. Seeded Plants
The seeded vascular plants are divided into: - Gymnosperms Have seeds that do not develop within an enclosed structure - Angiosperms Have seeds that develop within a protective structure

6. Although no one species of the 265,000 species of plants can be considered typical, the focus here is on angiosperms.

7. Plants have two basic organ systems:
Shoots and Roots

8. The Shoot System
The shoot system consists of stems, leaves and reproductive structures.

9. Stems are the framework for upright growth.
Terrestrial plants support themselves by means of thickened cellulose, cell turgor and xylem

10. Water, minerals, and organic substances are transported through the stems

12. The leaf has evolved to optimize photosynthesis.

13. The root system usually grows underground.
It absorbs water and minerals from soil and conducts them upward It stores food; it also anchors and supports the plant
There are taproot and
fibrous root systems.

14. Plant organ are composed of three tissue systems.
Vascular Tissue
Xylem and Phloem carry out long-distance conduction of water minerals, and nutrients within the plant
Provides support
Dermal Tissue
Outer protective covering
Protects against physical agents and pathogenic organisms
Prevents water loss
May have specialized structures for various purposes
Ground Tissue
Consists mostly of thin-walled cells that function in storage, photosynthesis, support, and secretion

15. The vascular tissue distributes water and solutes through the plant body.

16. XYLEM
Conducts water and dissolved ions absorbed from the soil

17. XYLEM
It is formed from two types of cells that are dead at maturity - Tracheids are long cells with overlapping ends - Vessels are shorter cells joined end to end to form a vessel.

20. Phloem transports sugars and other solutes throughout the plant body

21. PHLOEM
Contains living conducting cells called sieve tube members
Companion cells, adjacent to the sieve tube members, help to load sugars produced in leaves and unload them in storage and growth regions.

24. The dermal tissue system covers and protects the plants surface.
The epidermiscovers the primary plant body

25. Dermal Tissue
Epidermal cells are typically non- photosynthetic and are relatively transparent , allowing light to penetrate to deeper tissues.

26. Dermal Tissue
A waxy cuticle covers the external surfaces of the plant to restrict water loss and resist microbial attack

27. Dermal Tissue
The periderm replaces the epidermis when roots and stems increase and become woody.

29. The ground tissue system makes up the bulk of the plant body
Functions are photosynthesis, storage and support

30. Ground tissues are composed of three basic cells types.

32. Parenchyma is the most abundant type.
Thin walled, pliable cells, found in virtually all plant parts. Various types participate in photosynthesis, storage, secretion, and other tasks.

33. Collenchyma cells help strengthen the plant (for example, “strings” in celery).
They are commonly arranged as strands or cylinders beneath the dermal tissue of stems and stalks Cell walls become thickened with cellulose

34. Sclerenchyma cells provide mechanical support and protection in mature plants
Walls are thick and often impregnated with lignin, which strengthens and waterproofs cell walls
Sclerenchyma cells form fibers, such as in hemp and flax